[LJFried]

HI
Did you check
Volume on phone calls - Samsung Community - 2733425

if that is you - re play store - I could not find one reported as reliable, the ones I found all had reviews that they enabled nothing that the device itself did not and simply provided a separate method of doing what the device did

Have you made certain side key - vol up is changing call volume and not only media vol
as
here
Ensure that the volume on your device has been set to the highest level during a voice call. You can also try tapping on the speaker to see if this improves the call volume.
During a voice call, press the volume button located on the left side of your device, and then tap on the drop down arrow to open the volume settings.
Tap and drag the Call volume bar to the end to maximise the Call volume settings.

Incoming call volume - Samsung Community
not the same model but I am sure same principle will apply

and

Solved: Call Volume - Samsung Community

thank you very much but there's no volume button on the left side and I didn't see a drop down arrow

 

[LJFried]

yes, of course I understand what a speakerphone is. It just seems weird that the sound should be so low. Thanks again.

 

[LJFried]

Certainly but that means that your conversation is not private and you risk the chance of bothering those around you, though you naturally don't intend to. Last year I was having breakfast at a local place. A woman a few tables away had her phone on the table with the speakerphone on, while she was carrying on a conversation. When I (politely) asked her to either turn the speaker off or continue the call outside, she looked at me like I was doing something wrong. Like I said, I think it's strange that you can't increase the volume on a phone call. Thank you again for your help with this.