Help with fixing tinny/boxy/muddy audio talk

https ://manual.audacityteam.org/man/bass_and_treble.html

Cut as much bass as is tolerable, as the roomy/boxy reverberation is mostly in the bass.
Boost the treble to un-muffle, (you will need to de-ess if you do, as the sibilance will become excessive).

An expander plugin (like couture) can reduce the room reverb a little, (but it’s mitigation, not a cure).