Best way to get access (legally) to another person mobile phone

I need to give remote assistance to another person by accessing her android mobile. Is there some app like TeamViewr or Microsoft Teams for Windows that allow the person in need of assistance to give control of their mobile to another person remotely? Are they safe? I mean I should be the only person who, upon request, should be able to do that. Question was kind of already posted here https://android.stackexchange.com/questions/84729/fully-control-android-phone-from-another-android-phone-over-the-internet but it's pretty old.