It is very common request, you should specify in which band, technology, etc. As 6G communication systems cover mmWave, THz, Li-Fi, MIMO, AI, UAV, etc.
6G doesn't exist yet, only a sequence of technologies (like the on that Ahmed Nor mentions) that research develops in hope that they will be useful when 6G begins to be standardized.
Based on what kind of software you are looking for, you might like: https://developer.nvidia.com/sionna
I'm sharing simulation code to academic papers on my Github: https://github.com/emilbjornson