en_obs-tn/content/24/05.md

He is so great

This could be translated as: “He is so important.”

I am not even worthy to untie his sandals

Untying the straps of sandals was a duty of a slave. John was saying that the one who would come is so great that John was not even worthy to be his slave. (See: rc://en/ta/man/translate/figs-explicit)