I have a iphone 7 plus, but I'm having a hard time hearing people that call all of a sudden. Is there a volume button to turn louder?

I have a iphone 7 plus, but I'm having a hard time hearing people that call all of a sudden. Is there a volume button to turn louder? - 1

Yes

I'm an iPhone 6s User.
I had this problem, you just got to make sure that it doesn't think that it's on the headphones setting while it's actually on speakers. Try turning it off and back on again or take it to the Apple Store.

The one trick that I used was that I just decided to talk to someone through the phone via my headphones instead of going through all of this to just restart it.

The volume buttons on the side of the phone.

The "volume" button is only for ringing, not for hearing people on the other end of the phone.