I wanna make some edits to songs where for example all notes are a single note or it’s in G minor or whatever. Is there some type of plugin or audacity setting that can do that? I’m on Audacity version 2.3.0
The current version of Audacity is 2.4.2 and it is available via the Audacity website: https://www.audacityteam.org/download/windows/
You may find the “Getting Started” guide helpful for learning what Audacity can do: https://manual.audacityteam.org/quick_help.html
where for example all notes are a single note
I don’t think Audacity can do that. I’m not sure why you’d want to do that…
[u]Melodyne[/u] can probably do it.
or it’s in G minor or whatever.
Yes, you CAN change the key with the [u]Change Pitch Effect[/u] but it changes ALL of the notes/music by a certain number of notes/semitones (or by a percentage) so it’s helpful if you know the existing key if you want to end-up on G-minor. And, it will still sound like music. 
I have no idea what you are asking for. Can you be a little more specific? Did you have a certain youtube video you wanted to share?
Something like these videos:
I forgot my login info for a bit so I couldn’t respond
Have you tried Gsnap ?
I don’t know how to use it, I can turn everything off and it sounds the same, I can turn everything on and it sounds the same, I can set everything at like 50000 different configurations and it all sounds the same except for tiny changes like it goes 0.01% louder or there’s half a wave of static noise in the middle somewhere. I’m better off manually drawing the frequency waves than using this tool
Yes, there are certainly a lot of possible configurations! 
I had toyed with this tool a little while ago and was moderately successful at “auto-tuning” up some flat notes on a sample track with only one voice. For your requirements, I suggest looking for internet videos on how to use gsnap, or other possible plug-ins. 