Here's the harsh truth - if you're seeing fat, unattractive girls on Tinder then it's a reflection of how others see you.
Tinder's algorithms are pretty simple and a major component is desirability. This is determined by how many people swipe right on you and your profile pictures - yes, when you upload a picture they're rating how attractive you appear in it.
This doesn't necessarily mean you appear unattractive, but it makes it more likely than not. Optimize your physical appearance and upload a variety of photos that show you with friends, in social situations, etc., and make sure you're appearing attractive in the photo - genuine smile, express through the eyes, etc. It blows my mind how many guys still post profile pictures taken while starting into a laptop webcam with a confused look on their face.
Tinder absolutely has plenty of hot girls. I met my girlfriend on Tinder and when I had an active account I was getting notifications constantly through the day. To be fair I do have a very unique look being so jacked with long hair and a beard. I highly recommend that look if you can do it as it's very popular right now and few pull it off well - Alex Hormozi, Liver King, Jujimufu, etc.