That’s a lot of points for POP3
But the Grid is under the Meshing settings , when you slide it up you will see the Grid size will adjust , make sure you reach 0.1 Grid settings while sliding it up … or less in this case as from my experiences it have lots of points and that will cost good amount of memory to process .
You see POP3 was not made for scanning human bodies , even if you can you need to have proper amount of RAM to process scans like that , this is not the software fault.
For full bodies you need at least 64GB of RAM .
You see the GRID don’t even allows you to get to higher point to prevent crash of the system .
Use lower resolution for meshing around 5 level may help .
There is no way around , or you get better system RAM or you will get lower resolution scans .