oneplus 6t

View: https://imgur.com/a/z4Dm7wz This is the battery usage I am getting on my phone is this normal?

I'm really hoping someone with experience will be able to help me. I'd be deeply grateful for guidance. I'm looking to buy either the bluetooth K480 or the K400+ for my dad who uses a OP6T. I've been reading for days and cannot clear answers to the following questions: 1. At some places it...