From what I've read from the OP and the other guy, you need to spend less time searching for fat porn. You don't need to give it up, but you show all the signs of it becoming a problem.
Get to the gym, get fit, put on some body muscle, indulge in a hobby you like (porn isn't a hobby it's a bad habit), purposely keep away from so much online media consumption. You're rotting your brains through media fat porn, and it will get worse and worse unless you re-balance yourself.
Porn itself is an unrealistic fantasy to make you knock one out. Dating a 400lbs+ woman and having a life with her is fucking hard work, but porn makes it look glamorous. Tips on quitting it as guys in their early 20s? Go fuck a 400lbs woman. That will probably help you quit, or put your expectations back to a more realistic level.
I'll probably get some loser come back at me for this, but go and have an honest several night conversation with chatgpt about how you think you've got media and porn addiction. Chat AI has moved on considerably. You will learn a lot about yourself (and you can do it anonymously, or create a new email so you can do it away from your regular online presence).
I'm in my mid 40s now and I did it 18 months ago, it made me realise a fucking load of things, it was a good life re-evaluation. I started out with being honest that only 600lbs women in porn is now my baseline, where did it come from, how did it escalate, where it might have come from in my first dating as a teen. How do I not not fancy my wife when she is 300lbs (but the sex had become massively infrequent). You'll find a lot of answers, or rather it will make you find those answers, but the biggest thing is being constantly online, there's a time and a place for all of it.
Look up what JOMO is and actually means, and then think, when did I actually last unplug? You're better for it. Everything in moderation, and you being in control of it.