You can ask at check-in and the gate, but not much more you can really do.

In 15 years of flying Lufthansa, I often asked but only managed to volunteer to get bumped once. On big travel days in Frankfurt they used to have a paper list of flights that were significantly overbooked at check-in, but my flight was never on it. When asking at the gate, having checked luggage and being on a connection through FRA seemingly made me less desirable or the overbooking was resolved by people misconnecting or not having the correct travel documents.