How to script an effect on all NPCs on game-startup

[Okradion]

I'm using a FNV GECK for modding.

I'd like to make it so every NPC actor in the game receives a buff to health and damage multiplier, on startup. It's a part of my in-progress rebalancing mod, and I've already done the same for the player, in the form of an innate perk (+250hp, 250% damage output) that the PC gets on game-start.

I could do it individually for each actor via perks/effects ofc, but that's a lot of work, and it wouldn't affect mod actors which don't rely on in-game actor effect templates (I noticed that a lot of quest mod NPCs basically use their own templates). I want a way to do it all at once, via script, that would affect every NPC in the game, vanilla or modded. Also I'd like to have several 'tiers' of buffs, if possible. Eg. +150hp/150% damage for "civilian" npcs, +250hp/200% damage for "easy" NPCs like raiders, Fiends, basic NCR troops and other and trash mobs, +400hp/300% damage for "medium" NPCs like Rangers, Khans, veteran Legionaries, etc, +650hp/400% damage for "boss" named npcs, etc.

What would that kind of script look like, broadly? I don't really know much about scripting, beyond very basic AddPerk scripts which I copied from the PsychoEffect script.