SPL Meter phone app.

NIOSH is what I put on the iPad and iPhone.
There are likely others too.

I’ve had good luck with decibel app on iphone. Have used it and test signals to help tune in a subwoofer on multiple occasions. Also to help know when I may be going too loud and potentially damage hearing. I suspect all of us might agree we all cherish our hearing ability.

er, I meant if your phone still supports a plug-in socket for a head piece...

Autio Tools on Android works great.  If you have a plug-in mic, I recommend the Dayton audio calibrated mic, about $20 and Audio tools will accept the calibration file.

https://amzn.to/39RnJ3D