The inversion here emphasises the part which is moved to the beginning of the sentence:
"You will only be able to see the spots on the sun if you look through this dark glass" - no emphasis.
"
Only if you look through this dark glass will you be able to see the spots on the sun" - the inversion emphasises that the effect will only happen if you
first place the dark glass in front of your eye.
"
Not until she took up rock climbing did she overcome her fear of heights" - the inversion emphasises the fact that she only overcame her fear of heights by
first taking up rock climbing.
wordreference.com - careful-as-she-is-she-had-an-accident.2895005
etc..
.