sliding into harder stuff to get off and I know it's a clear sign of porn addiction.

Is it? I think you know best if you have a problem or not, so more power to you abstaining if you feel you should, but watching like, fetish porn or whatever isn't inherently a sign of addiction IMO. Just to get that out of the way.

I go back and forth on porn myself. It's a nice aid to get off sometimes, but I also find it sort of desensitizes me in a way I don't like, its hard to find porn that isn't... icky, in terms of how it portrays sex and gender and etc. and sometimes I feel it dulls my desire to like, actually look for a real life partner, so I've gone stretches where I just didn't watch it, and used toys or fantasized about past partners, etc. instead to get off when I wanted to, or sought out a hookup (easier if you live in a big city and have grindr as an option, probably much harder for the average straight man I suppose). Getting off without the visual stimulus of porn seems really difficult if that's all you're used to, but it really isn't for me at least, as long as I am in the right headspace (horny, mainly I guess, but also just like not uber depressed/stressed). It takes a little longer to get there but it's much more gratifying IMO.

If you'd rather abstain entirely that's also an option but I don't think there's a lot of specific advice I can give on that, you just have to choose not to masturbate. don't keep toys or lotion/lube or tissues or whatever else by your bed/wherever you usually do it. don't have sites bookmarked or whatever, or don't sub to that kind of thing online if you don't want to see it and be reminded. from what I've heard you could also just get on certain SSRIs lol. And I second what FourteenEyes said, if you think maybe its just a boredom/lack of stimulation thing, then you have to have other shit to do, whether it's reading, touching grass in some way or another, walking and listening to podcasts, or some other shit you're into/want to be into.