To all those saying that enemies don't follow the same rules as players... Yes. In 5e, they generally do.
For example....
Archmage is a CR 12 creature, able to pose a moderate but not overwhelmiong threat to a group of 3-4 level 12 player characters.
"Spellcasting. The archmage is an 18th-level spellcaster. <snip>
The key point here is that the Archmage is a CR 12 creature but an 18th level caster. So in BG3 it'd be given the designation of "level 12" but would be able to cast 9th level spells, something no level 12 player can do.
Similarly,
I am not so sure, in the goblins hall there was a lv2 human wizard who cast Command a ridiculous amount of times.
A "level 2" human would likely be a 3rd- or 4th-level spellcaster, which would give them access to 6-7 spell slots.
As Niara and Aishaddai said, a enemy with a CR of X needs to pose some kind of threat to the
entire party, which is why they often have better abilities (spells, multiattack) then an equivalently-leveled party member.
