There are many sports clubs offering children and youth sports. Please ask for information at the local sport clubs.
An overview of sports and sports clubs in the state of Rheinland-Pfalz can be found here: https://www.lsb-rlp.de/images/stories/fachverbaende/allgemein/02_18_Adressen-FachverbaendeRLPneu.pdf
http://www.sportbund-rheinland.de/index.php?id=27
https://www.sportbund-pfalz.de/sportvereine-in-der-pfalz.html