If I buy a new iPhone, will I lose the location sharing with my friends?
Solution 1:
If you are signed into iCloud on the old and new devices, your location sharing ("Find My") settings will carry over. iCloud is required to share location anyways - so you just need to sign into the same account.
You can verify this is connected to your iCloud account by signing into iCloud.com and confirming that everybody shows up on the web as well.