Anything can be painted with the proper prep and pint. Should anything be painted is the big question. What material is the trim? Pictures?

If you have bronze aluminum framed windows, then no, there’s not much you can do. Rustoleum spray paint would probably stick and look nice, but how to pain a narrow strip of metal without making a mess? A brush would only leave marks and look terrible. Plus, do you paint the whole track (assuming the window opens)? The paint could interfere with working the window and it would definitely chip off in the track.

What millworkman said. If the metal is aluminum, an aluminum primer needs to be used. If steel, steel primer. Galvanized---there are several types. Metal must be clean and dry to start. Proper finish type paint has to be used---approved for water contact.