21 yo, and gifted $50k from my grandma. How to invest, besides maxing out?

Hi, my grandma is gifting me $50k for graduation. Insane, because she’s never given me money growing up. What should I do to invest? I’m on Medicaid rn to see if I qualify for surgery soon, so I don’t want to accept it yet so I don’t lose that benefit. Please give me advice 🙏