So confused since I think GeForce Experience messed with my settings… I reverted back to the High preset but it changed other things like FPS min to 60, max to 300, and this render scale. I change FPS min/max both to 300 and render scale to custom with a min/max of 100.
With the automatic one you might experience some frame rate drops here and there. I’ve heard people saying the custom one is better.
Unless you’ve got some the graphics card and want to make videos then just set the render scale to 100. As for FPS, just set it to the max rate that your monitor can handle 
If you set it to automatic then you may end up with strange variances which may help make things run smoother when things get busy (albeit very jarring visually), but it’s probably better to just find the max settings your rig can handle at all times and leave it at that.
I made minimum render scale 100%, maximum render scale 100%, minimum FPS 300, maximum FPS 300 (I still cap out at 142 in game since my monitor is 144hz - I play at 1440p). I think I have a ‘boost’ monitor (forgot exact name) that would technically allow 165hz but don’t care about that.
What I described my settings above is no issue right? Seems to work for me.
That should be fine, I’m surprised you can’t just set it to render it at X though rather than always having min/max 
I guess you have in a sense. Oh well, more options are good.
As for 300fps vs the max you can display… This is where you may want to do you own research. Anecdotally I’ve been told that there’s no point but (also anecdotally) others have said it may improve latency between your you and computer peripherals and the game with (not the server!). Assuming that you don’t have any lag/issues running at a high frame rate than what you can see, I’m not sure what the downsides are other than taxing you machine unnecessarily
keep it at 100 min/max. I had geforce mess up my overwatch settings by trying to render the game in 4K which drastically reduced performance but not much for image quality because my monitor was not 4K. I have never had Geforce installed ever again
What about 300 fps min/max? Shouldn’t matter either if I only get 144 max anyway right?
It’s matter,higher fps means less input lag
if your monitor is 144 hz then not much point in having it above that. Although i’ve heard arguments for having it slight below your native refresh rate, as well as slightly above. If you aren’t worried about power usage or heat output in your place, as well has have an abundance of processing power in your machine you can have the max FPS at higher. When I had a 144 hz monitor i kept the max at around that for aim consistency (even though my machine could do 300 FPS), but yes as Keyser says the higher the FPS, the higher the chances are that your monitor grabs a slightly newer frame which helps reduce the input lag. But, may reduce consistency as FPS dips during fights, etc.