You don't need a dumb phone, you just need decide who's in charge. I used to want a dumb phone, but there are a few things (mainly maps/navigation) that I find genuinely useful that dumb phones can't do.

So I decided that it's my phone and I'm the one who decides how to use it.

I have a reasonably new iPhone. I spend maybe 15 minutes a day on it (excluding navigation), total.

I have removed apps I don't use. I disabled Siri, FaceID, most notifications, and location is turned off unless I'm using maps. I have one page on my home screen and there are maybe a dozen apps on it (and that still includes a few I have never used so I could pare down further).