I was asked to do this for my MacBook repair and I asked them why. The technician said they had to run their diagnostic tool to make sure everything is in order

I was asked to do this for my MacBook repair and I asked them why. The technician said they had to run their diagnostic tool to make sure everything is in order. But he simply asked me to create a new limited access user rather than give out my password. Unfortunately this doesn’t help your situation, so I’d recommend taking a full offline backup using iTunes, erasing the phone and restoring your backup once you get the device back.