The goal of this clinical study is to learn more about the study drug lenacapavir (LEN), safety, tolerability, and pharmacokinetics (how LEN is absorbed, modified, distributed, and removed from the body of the participants) of once-yearly intramuscular for HIV pre-exposure prophylaxis (PrEP) in people with an indication for PrEP. The primary objective of this study is to evaluate the pharmacokinetics (PK) and the safety and tolerability of intramuscular (IM) every 12 months (Q12M) LEN for PrEP among people with an indication for PrEP.