To identify the passage from O. Henry's "The Gift of the Magi" that best expresses the theme that true love is not dependent on appearance, you'll want to consider the parts where the characters, Jim and Della, make sacrifices for each other. The ending, particularly, highlights that their love is based on their selflessness and the depth of their feelings rather than material possessions.
In general, the essence of this theme can usually be found in the parts where Della sells her hair to buy a gift for Jim, and Jim sells his watch to buy a gift for Della. These actions illustrate that their love transcends physical appearances and is rooted in their willingness to give up their most prized possessions for each other.
If you have access to the specific sections you mentioned, look for passages that highlight their sacrifices and the interactions that emphasize their love beyond material things. If you provide the text from those sections, I can help you analyze them to find the most suitable one.