No PowerMac can act as an external monitor for another Mac. Only a limited set of iMacs with Intel processor could do that.
Also, no 2020 Mac including the M1 models can make advantage of the now-deprecated Target Display Mode, even if you have a supported iMac. It is dead tech.
As for a wireless connection, we need to know what a "PowerMac 6" is. That is not standard Apple model nomenclature. To get the actual Apple description, you can entry the computer's serial number in this lookup page:
https://everymac.com/ultimate-mac-lookup/
and it will return the sub-model. Post the sub-model but NOT the serial number.
The reason this is important is that PowerMacs were in production from 1994 to 2006; older models have no practical way to connect wirelessly. Newer models have different options.