We have the Avenza maps app, and splurge on Benchmark state Landscape Atlas maps to easily identify BLM and other agency lands. They are not cheap, and take up a LOT of space on my phone.
They are active maps- you can see your exact location on the map. It makes it easy to be sure you're squarely on the right piece of dirt for legal free camping.
When we started using them, we discovered loads of good boondocking possibilities that have no special names and/or aren't listed and reviewed to death on the internet.
You can go wrong by not knowing the area's ground type (deep sand, sharp aa, thick vegitation, nowhere flat to pull off, etc.) But if you're willing to take chances on long gravel and dirt roads to scout, it can be really rewarding.
The maps designate what kind of road is what. We didn't pull our little trailer down roads designated as 4wd or unimproved dirt without first trying it with our 4wd tow vehicle.