What is the maximum decimal output of iPhone earbuds?

I want to make sure I do not hurt my ears.

According to some people, the max is 100 decibels from them. However, where did they get this from? Is this measurement taken from right next to it?

People do not recommend more than 85 decibels because after that hearing loss is only a few hours. 85hrs over what time? Per day, per week?

Anything over 85 dB for even an instant can be hazardous,
but of course it isn't as bad as higher levels and/or longer times.

For speakers, the SPL is measured at the listening position in the room.

For headphones and earbuds, there are special methods that either
mimic the ear canal or give results that can be considered equivalent.