Yes.All the websites that offer free spin bonuses to win real cash prizes do so after you have a registered an account on their platform. They do so not only because theywant you to register and try their services, but also because they need to make sure you are legally allowed to gamble online.
The most obvious benefit of playing free online slots is that you don't have to spend any money. This means you can try a game out without risking your bankroll on something that you may not enjoy.