Warning: Minor spoilers ahead if you haven't watched the entire series.Rosa first comes out to Detective Charles Boyle, unintentionally.
She knew that Charles couldn’t keep the secret to himself. Rosa, being the badass bisexual she is, takes control of her story and the narrative and decides to come out to the squad.It's no secret that having a queer role model to look up to makes it countless times easier for young queer folks to accept themselves and come out.