In Family Search, sadly, there is no obvious indication of when a child is adopted into any particular family.
Family Search should have a little quarter-inch dot that can be marked (or is marked) next to the name of any person in a family tree that was adopted; visually, it explains a lot when a person is part of a family, but their birthdate, etc. doesn't fit with a particular family. This is different from one who was merely raised in another family, be it with a relative or otherwise.
PLEASE develop a FamilySearch family tree in which an adopted person can show their birth family on the left side of the family tree (as in a circular version), and the adoptive family tree can be on the right side. People like me want to see birth and adoptive lines ON ONE CHART- I want a chart that I can click on, on any birth or family member/family, and work on family history and temple work. Even current charts or setup are still annoyingly complicated and make going from chart to chart a major headache for those of us who are adopted.