1. ... Rd1+
2. Rxd1 Rxd1+
3. Kf2 Qxh2+
4. Ke3 Qg1+
5. Ke4 f5+
6. Kxf5 Qg6#
There is one slight variation on this sequence of moves. If you cannot see it, post a comment below and I will add it.
This position is from Nick Maatman versus Luuk Baselmans, Dutch League, 2022-23. Black to play and checkmate in 6 moves: