This study is for adults with HIV who are currently being treated with Biktarvy® (bictegravir/emtricitabine/tenofovir alafenamide [B/F/TAF]). The purpose of the research is to compare the effectiveness of B/F/TAF and the investigational once-daily medication Bictegravir/Lenacapavir (BIC/LEN). Participants will either continue taking B/F/TAF or switch to BIC/LEN for at least 48 weeks. The study will also look at the long-term effectiveness of BIC/LEN. Participants will be given the option of participating in an open-label phase of the study (where both the provider and participant know which drug they are on) where all participants receive BIC/LEN.