How do I find out if someone has set up family sharing on my account because it wasn’t me
Why is family sharing on my phone
Why is family sharing on my phone
Go to Settings > [name on top] > Family Sharing, to see if it has been set up. To set up Family Sharing the request has to be approved on your phone, so someone would need to have physical access to your device and account to be able to accomplish that. It cannot be done remotely. If you feel your Apple ID has been compromised then follow these steps.
If you think your Apple ID has been compromised - Apple Support
Follow this support article to run a Safety Check on your device to see your list of Trusted Numbers and who is logged into your account as well as what information you are sharing.
How Safety Check on iPhone works to keep you safe - Apple Support
How to find out how many Apple ID on my account
how do I see how many I’d I have on my account
How do I find out if someone has set up family sharing on my account because it wasn’t me