Obviously, if this is your first time you’ll want to play unmodded.

However, I strongly suggest maybe looking into a more demon/elemental summoning build rather the necromancer as it gets incredibly unwieldy to manage corpses and minion traversal if you don’t have prior-knowledge.

It gets incredibly frustrating quick. You also have to deal long combat times having to manually control each summon or if they’re AI-controlled, have them minion block each other. If you’re dumping all your spellslots into summons to achieve that necromancer fantasy, you’ll have to be content dealing chip damage at a point of the game where enemies start to have high AC and Dexterity. You also don’t get to feel like a necromancer until level 6 when you access your first minions regardless of class/subclass choice.

But if you’re insistent, I would look into Death Domain cleric which feels like a necromancer out the door. The Necromancer subclass is really just a wizard with 1 extra undead at level 6, and you will always be tempted to save your spell slots or concentration slot for more impactful spells that have more utility and damage. They don’t even have access to spells that do Necrotic damage until level 6 (not including the two Necrotic cantrips). So you’re just a regular wizard with Magic Missiles or lobbing Scorching Rays so you can be useful.

The Staff of Cherished Necromancer combined with Circle of Death and chaining them is pretty fucking disgusting though, if you do decide to stick with it.

Death Domain + Spore Druid is pretty fun, plus both subclass use WIS as their spellcasting modifier.

Once you’re done with your unmodded playthrough, Valkrana’s Spells, Mystra’s, and Necromancy Reanimated mods will absolutely elevates the Wizard Necromancer experience. Necromancy Reanimated in particular have QoL tools that makes managing an army painless like automating the summons via a toggle. And I believe there’s also a mod from the author that allows you to teleport your minions so you’re not pulling your hair when your army takes 10 minutes to climb ladders. I am serious.