Public lands.
Check out that BLM life. There's plenty of it out there. Also there's some apps for finding camping spots. I can't remember the camping spot one I used to have. Sometimes just googled areas. Utah is pretty easy for what I've found. Have done a few trips camping around the nat parks/monuments, and other spots. Have had good luck. This last year we went through moab area on the way back to escalante and the one big area was the fullest I've ever seen by far. We had to kind of work for a spot in the back.
Idk really depends where you're going but a lot of times it's not too hard to find free places to camp in the west. Some places it's def more likely to fill up than others so getting a spot in the day is clutch. Sometimes I'd get a hotel once every week or two to have a bed for a night.
But people post about everything which helps spots get more crowded but also makes them easy to find. I was just googling free camping in areas and finding stacks of responses with roads, mile markers, landmarks etc, details and everything.