That depends on the size of your tent. If there is no tent and its an open room then you need to map out the light on the ground and go from there,
in general I think one 600w light can fit a 5x5 or 6x6 tent, but the light reflecting off the walls in it helps out a lot.
If its in an open room I'd do aorund 6 plants under one light in a tent 9. do SOG, a grid of 2x3 or 3x3 is also the same.
growdiaries.com/journal/how-to-grow-cannabis-with-sea-of-green-sog
https://dutch-passion.blog/growing-cannabis-with-the-sea-of-green-sog-method/
Cheers,