in parametric eq 10 band, lower 100hz-500hz geometrically less the higher freqs, and add subtle reverb, which naturally comes from trees and hills echoing.
Also, you can add noise from wind in leaves rustling(very small amount)
the actual db level would probably be a little lower too to seem more distant unless they are yelling.
Remember in a movie, not everything is 100% real as the viewer still needs to hear and understand the story.
I would rather have video I can’t see and good audio I can understand than visa versa, unless they are really good subtitles, jk.