Level audio in documentary

Adjusting your volume is pretty much a manual operation as each clip will have it's own needs.

Attach a quality set of headphones or speakers and LISTEN.

The human ear is much more accurate than a one size fits all computer routine.

Then adjust live audio, sound effects and music to suit.

Al

in addendum to Alchromas reply:

aside the 'felt loudness', there are technical boundaries, mostly 'broadcast standards', but cinema or disk-production ask for - diff.- settings too.

shift-cmd-8 opens the Audiometer, which gives you a clue, where you are, -12, -6, -4dB (it differs, no 'general' standard).

For hobby, my standards are:

Stay away from getting audio-peaks red .... 😀

This may help:

Final Cut Pro X: Adjust volume

Al