then you can buy a y-adapter. one end 3.5 connects to your phone and the other end two rca leads connects to the receiver.

something like this:

https://www.amazon.com/KabelDirekt-splitter-smartphones-notebooks-equipment/dp/B00DI89NPE/ref=mp_s_a_1_9?keywords=KabelDirekt&qid=1652509236&sr=8-9