Why are you worried about some number in the corner of the screen.
Even if you get it to work it is highly likely you are going to feel the lag between the controller input and the screen. All these frames are fake and do not represent input from you or even the games true output.
Part of the reason 1440p might appear the same is maybe the game is already putting out 1440p and the video card is just pretending it is 4k. This is fancy upscalling is one of the ways dlss makes it appear you are running higher frame rates than you really are.
You might be better off running it at 1080 and get the full 120hz rate but all the frames are actual frames coming from the game.
Not sure about star wars but other games like cyberpunk there is no GPU in existence that can run at high frame rates when you run stuff like ray tracing and high settings.....unless you generate fake frames.
There are youtube video that show side by side comparisons when you start cranking up the fake frames. You might get higher frame rates but the frames now are not as sharp and appear somewhat blurry.
If you were to turn off the FPS counter on the screen you likely would like the appearance of 50 or 60fts compared to 120fps with fake frames or just run 1080p and enjoy the game without worring about some number.
Other wise wait until a 6090 or 7090 comes out and you have a extra $3000-$4000 dollars for a card that can really render 4k at 120hz.