I dunno if this applies to an EV once it's been fully charge to 100%, but I asked the salesman about predelivery charge, he confirmed they arrive off the truck with HV battery levels of 10%-30%, dunno if he's accurate or not, but he was extremely knowledgeable about the EV6 since he owned one himself, so the grain of salt may apply.
For myself, my EV6 is kinda in storage all winter cuz I'm old and retired and don't drive much this time of year, I follow the advice of the Engineering Explained fella on Youtube and keep it tween 40%-60% and I only level 1 charge when needed unless I need a full charge for a trip which doesn't happen often until spring.....FWIW.