iPhone XS Max slow and restarts after dropping

I recently dropped my Iphone and ever since I dropped it there have been a few issues with it that have made it unusable. It is very slow to respond when I touch the screen, and when I open an app it runs very slowly. After a few minutes of being on the screen goes black, a flash happens on the bottom of the screen, and it automatically resets as if I fully powered it off and turned it back on again.

I wanted to fix this on my own but I am unaware what parts I should order or any methods to figure out what is damaged. I have no stores near me that can check what parts would be damaged, and I could go out to one, but I would prefer if I could figure out myself somehow.

If you could either give advice/methods as to how to find the problem, or suggestions as to what the damage may be that would be great!