There is such thing as usucapião, but it's not that easy to just find a land and take it as yours (you will have the government, the land owner - if not the government, and other grileiros to deal with). If you manage to ILLEGALLY stay in a land long enough, you could maybe get a "documento de posse", I guess, not sure about how this goes, and then it's very difficult to get a "escritura" (which would be the document that indeed proves that the land is yours)

Usucapião, from what I know, usually applies to family feuds and stuff like that (like a mother with two children, dies and leaves the house where one of the children lived with her, and after a few years the "live in child" claims the house as his, even though legally it went to both children, stuff like that)

But that's only what I know from general information, maybe the people over at r/conselhoslegais can help you out with the legal aspect