The game offers a small number of first-party servers, but anyone that owns it can host a dedicated server, or have their current play session work as a server by turning multiplayer on and sharing the invite code. You can also change several settings of your own server/world whenever you feel like, like material drop rates, experience rates, building deterioration, damage taken/done multipliers, stamina use, day/night length, etc.
I have the game, played it a lot, love it despite the bugs and somewhat frequent crashes. Save wipes after a crash are annoying, but I think it’s good that they happen to me, they help me stop playing for a while