BG3 is not based on Pathfinder, or Dragon Age Inquisition, or Gothic 2.
How the Necromancy class works in these games is irrelevant.
BG3 is based on D&D 5e.
Animate Dead in 5e works as below:
Animate Dead
3rd-level necromancy
Casting Time: 1 minute
Range: 10 feet
Components: V, S, M (a drop of blood, a piece of flesh, and a pinch of bone dust)
Duration: Instantaneous
This spell creates an undead servant. Choose a pile of bones or a corpse of a Medium or Small humanoid within range. Your spell imbues the target with a foul mimicry of life, raising it as an undead creature. The target becomes a skeleton if you chose bones or a zombie if you chose a corpse.
On each of your turns, you can use a bonus action to mentally command any creature you made with this spell if the creature is within 60 feet of you (if you control multiple creatures, you can command any or all of them at the same time, issuing the same command to each one). You decide what action the creature will take and where it will move during its next turn, or you can issue a general command, such as to guard a particular chamber or corridor. If you issue no commands, the creature only defends itself against hostile creatures. Once given an order, the creature continues to follow it until its task is complete.
The creature is under your control for 24 hours, after which it stops obeying any command you’ve given it. To maintain control of the creature for another 24 hours, you must cast this spell on the creature again before the current 24-hour period ends. This use of the spell reasserts your control over up to four creatures you have animated with this spell, rather than animating a new one.
At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, you animate or reassert control over two additional undead creatures for each slot level above 3rd. Each of the creatures must come from a different corpse or pile of bones.
D&D 5E allows you to have multiple undead but they are low level and can be blown away by a fireball or turned by an opposing cleric.
Should you specialize as Necromancer it's 6th level feature Undead Thralls makes your summons tougher with extra health and gives them better attacks.
As Early Access only gets you to level 4 we won't be able to see this in action until after launch sometime in late 2021.
As of last update only the Evocation and Abjuration Arcane Traditions will be available at the beginning of Early Access.
It is unknown when Larian will be adding more.
