German phone lines usually end with a TAE connector (Telekommunikation-Anschluss-Einheit):
The main question would be - will you have internet connection via that landline.
If it is a pure landline, it will use the TAE connector, and there are adapters for RJ-45 jack to TAE connector. I do not know however if the dial tones are different.
Anyways, pure landline phone - while still available - are getting exceedingly rare and most telecommunication companies will try to shift people from direct landline connections to VoIP connections however.
Almost all companies (regardless of (V)DSL, cable or fibre connection) should provide you with a multi purpose router with built-in analogue to VoIP support accepting either TAE or RJ-11 (sometimes even RJ-45) connectors for analogue or ISDN phones.
Also the most popular routers in Germany can accept either ISDN or/and (depending on the model) analogue phones with RJ-11 connectors and connect to the TAE socket themselves and act as a mini PBX.