Cpu pre-renders all frames according to game code and some in-game settings. The amount of frames it can pre-render in one second is your fps limit.
The gpu takes those frames and finish renders them according to graphic detail levels and resolution. The amount of frames it can paint on screen is the current fps.
So if the cpu can pre-render 100 frames, that's what the gpu receives, 100fps. If the details or resolution is too high, and it can only paint 60 frames then many people call that a gpu bottleneck. If you lower details very low, often that gives the appearance of raising fps, it doesn't, all it means is there's less work for the gpu, so it can finish more frames and paint them. But it's still limited to whatever the cpu sends.
Some games are so graphical simple, that even at ultra details, the gpu has no issue painting everything the cpu sends. Many people refer to this as a cpu bottleneck. It isn't. It's just one game where the gpu is not challenged.
In reality, a bottleneck is something that slows down the flow of information, chokes it. A cpu can never be a bottleneck because it's the source, the cpu puts out whatever it puts out, it slows nothing down. A gpu cannot be a bottleneck because it's not holding back the cpu, it doesn't slow anything down, it takes whatever info is offered and does what it can do.
And yet ppl still throw the word 'bottleneck' out there based on the assumption that whatever game is played it should always get maximum fps from both components in balance, equal, what goes in comes out. Doesn't work that way because games are vastly different. The Sims is nothing like Battlefield5 or CoD. CSGO isn't Gta5. Mmorpgs are nothing like single player games.
Bottleneck is the single most misunderstood and abused word in the pc world.
In reality, the cpu more often than not is stronger than the gpu. And in the games where the gpu is stronger, so what? Just means you could play at higher details without suffering fps loss, minimum frame rates are closer to maximum, gpu temps are lower etc.
A 1650 will be just fine with a 6300, you'll be more limited by the cpu anyway in many modern games. OC on that FX will help bring the fps limit up, maybe enough to start challenging the gpu ability to get all the frames on screen.