It's quite simple, and the GOP is putting it into practice all over the US. Wipe the rolls, and legitimate, albeit casual voters show up only to be told they aren't registered, and they can't vote, or they risk going to jail. Or, they are told they can fill out a provisional ballot, which may or may not be counted, or they just feel marginalized, and they leave.
This isn't 4D level chess what the GOP is doing. Establish a sense of hostility to keep people away from their polling place. Multiple states in 2020 were decided by tens of thousands of votes. The GOP sees voter suppression as a tool to cling to power. The last thing the GOP wants is a high turnout.