Thank you for the recommendation/request! Sorry about the lack of those options, this was my first game, so there's a lot of missing things. If I revisit this, I will add more options.
I have an Low End PC and is unplayable without any Option to change the Settings to increase the FPS. ^^
Most Developers doesn't care at all to implement Things like Resolution Scaling or an Potato Mode etc. We NEED those Settings because the Complexity rising in the Modern Games and eventually playing on the native Resolution is the bad choice to choose because of Performance. Instead we should get more Setttings/Options to increase the Performance one of them I mentioned earlier is "Resolution Scaling". This increase the Performance immense and helps a lot for Low End PC Users.
You can read a really cool Explanation from Godot here.