I'll do my best! Boy is this going to be a long post. I wish the forums supported writing math better and I apologize in advance.
The short answer is yes for practical purposes. Since you read about space travel as a hobby I'm going to assume you know what deltaV is, if not it's basically a metric of how much you can change your orbit. It's easier to measure it in terms of energy/velocity rather than distance because distance between 2 points varies in an orbit.
Knowing this, given an objects mass we can solve for the velocity necessary to obtain an orbit. Orbital Velocity also varies dependent on altitude, but that is bounded below by sqrt(G*M/R) where G is the gravitation constant, M is the body in question, and R is the distance from the center of mass, or radius + altitude.
So we could conceive of planets that are both more massive and that are larger that would require more deltaV to reach orbit. That may or may not also translate to a 'taller' atmosphere that also represents a lower bound to the orbital velocity. For example, we could orbit at 50km, but the atmosphere presents too much drag and it's simply not possible without continued thrust, so we target higher orbits where there is less drag.
Lets take a look at Earth 2.0. Earth 2.0 is everything Earth is but twice as large. Twice the mass and twice the radius! This makes it easy for me because I already know that Earth 1.0 requires 7.8 km/s of deltaV to orbit at around ~400km, but practically requires around 9.5 km/s of deltaV from losses due to drag and gravity. This means that Earth 2.0 requires 15.6 km/s and I'll assume it takes 19 km/s for simplicity. In all likelyhood it's more due to the fact the atmosphere is probably thicker and you take twice the gravity losses per second. Ouch.
Looking at a deltaV map to save myself from doing the math, just to land on the moon requires 9.5 + 3.2 + .68 +1.73 or 15 km/s. It would require another 1.73 to get back to low lunar orbit, then ~ 1.6 to lower your periapsis into the Earth atmosphere and aerobrake to the surface. This totals us at 18.44 km/s. It's debatable, but using all 5 stages of Saturn V it still might not be able to reach orbit on Earth 2.0.
So with current chemical rocket technology, we might be able to reach orbit on Earth 2.0.
To make it as simple as possible, the reason for the :
is because of how the rocket equation works.
The rocket equation, as stated above in another post of mine, is deltaV = Isp * g * ln(m1/m0)
Isp is like the mpg of your rocket engine, but it's really just exhaust velocity/g. We normalized it to seconds during the cold war so we could compare the stats of rocket engines between us, the europeans, and the russians without doing all these conversions between 5,000 m/s or whatever that is in ft/s.
The most important part is the ln(m1/m0). This is where that issue of adding fuel which needs more fuel to propel is described in the math of rocketry. This is called the mass fraction. m1 is the spacecraft + fuel and m0 is the spacecraft empty. Because you're taking a logarithm of this, even if you double the amount of fuel, it does not result in a similar increase of deltaV. ln(2*m1/m0) is the mathmatical representation of that and you can plug in numbers in a calculator if you want to play around with that. Just know that m1 > m0 for obvious reasons.
The other alternative to increasing your deltaV is to increase the Isp, which is the exhaust velocity of your engine. Basically, make your propellant leave the rocket faster, and it imparts more energy for a given quantity. This makes sense because kinetic energy = .5*m*v^2.
There is a theoretical upperbound on the amount of energy stored in chemical reactions due to the potential energy of chemical bonds. So for a given propellant mixture there's only so much you can do. It turns out hydrogen and oxygen is one of the best bipropellants for a variety of reasons. I won't go into it unless you ask a specific question, but if you're interested in rocket fuels I recommend reading Ignition! by Clarke. It's available for free as a pdf around the internet. The maximum Isp of hydrolox is something like 500s give or take 20%. We've managed to create an engine(Space shuttle main engines/RS-25) with an Isp of 455! That's pretty damn close to the max.
So I've been pretty scattered about this because there is so much material to cover so let me try to pull the pieces together. To get enough orbital velocity on a greater planet you need to use a combination of: Splitting up the rocket into multiple stages(creating better mass fractions with each stage produces better overall deltaV), increasing the mass fraction of each stage(More fuel per stage and lighter structures, engines, electronics, etc), and increasing the Isp to maximum possible(This could be done using hydrolox, or exotic tripropellant mixes, or nuclear rockets). Those 3 techniques each come with their own challenges and Earth 2.0 would be an absolute nightmare to get off of.
There's a lot I skimmed over or just didn't mention so if something isn't clear let me know.
Part 2. Nozzles.
There is a simple analogy that kind of glosses over the details but I hope it will suffice. Ignore the combustion chamber and pressures and all of that. When you burn fuel, its product wants to exit. We want those products to exit exactly downward if our rocket is moving straight up. This is because otherwise the exhaust might move a bit sideways and you don't get 100% of the momentum possible out of that reaction due to the sine losses of that. I hope that makes sense. Basically if you're trying to go straight up, but you have particles not moving straight down, you won't get the most out of those particles, thus reducing the overall energy transferred to the rocket which is a reduction in it's Isp.
Now we can talk about pressure. The ambient pressure helps push those exhaust particles back downward because that's what pressure does. It pushes stuff from all directions. I really hope you can visualize it because I'm having trouble explaining it. Without pressure, like in a vacuum, there's nothing to stop a greater percentage of the exhaust from moving at an angle, so it requires a larger/longer nozzle to make sure a greater percentage moves straight down. This is called the expansion ratio of nozzles if you want to do more indepth reading.
I don't follow. There isn't a gaseous step before the combustion chamber. Gas likes to react with things and propellant reacting before the combustion chamber would be bad news. Is this related to the COPV bottles of helium SpaceX uses to pressure their fuel tanks? If so, the reason is that, unsurprisingly, as you burn propellant it will leave the fuel tank. Try sucking on an empty water plastic bottle and see what happens. The helium is to keep the fuel tanks at the same pressure so the tank doesn't implode. Very necessary.
Edit: @JB47394 mentioned economics and is pretty much the reason why pushing the limits that I mentioned would be difficult. It would be very impractical.
Edit2: here I am trying to get to sleep hours later and I realize I screwed up my math. Orbital velocity and general gravity for Earth2.0 should be about sqrt(2)*Earth. This explains the slight descrepency between barely making it for me and only 4 stages with JBs source. Check your math people!