How to generally get better at Apex? I'm nintendo switch level 20

@hype_f0rceJust play, and try to learn from your mistakes. Dropping hot is not gonna do it, because the game is not just mechanics. Mechanics will come with time and practice naturally. Spend 8-12 hours a day playing, and you will improve.
If you do not have such time at hand, find something else you wanna get good at that you already are doing, such as school or work.