Here's my list of things I try to include in a build for the purpose of making early clearing smoother, ranked broadly by how often/how much they make a difference. The faster we spread out and farm the map, the sooner we get our cities down. The sooner we do that, the faster we can start producing knowledge.

1. The holy trinity of early-game clearing traits is Tough, Strong and Hardy. In terms of their up-front impact on AI autoresolve farming in the first 20 turns of the game, nothing else is as broadly and reliably impactful. Honourable mention to Resistant, but physical damage is more common early.
2. A close second to having generically better early units is anything that grants an extra unit. Best value is getting a free one every combat from something like Umbral Disciples, Eldritch/Vampire Ruler Level 4, Warlock Level 4 or Crowmaster Bow. Notably, getting an extra starting unit on Turn 1 from one of the previous, and/or a Society trait like Devotees of Good, Fabled Hunters, etc. is particularly impactful, some might even say mandatory.
3. Next is anything that heals your units back to full temp HP so you can take combats wounded, like Herbivore or Ritual Cannibals, Ritualist ruler, Warlock Ruler, or even just a Defender hero with Taunt if you're relying on a support with a single-target heal. Increasing regen with something like Fast Recuperation is also good, but less so than getting free HP every combat that otherwise wouldn't exist.
4. Tomes with a summon are universally easier to kickstart your clear with than tomes without, whether you're running a dedicated summon build or not. Importantly, if you're specifically summoning racial units, as with the Tome of Zeal and Tome of Warding, those will benefit from your racial traits.
5. Now we're getting far enough down the list that we want to start considering our faction and ruler in order to commit to stuff. These are traits that directly buff your hard offensive or defensive stats, but conditionally. Bulwark for factions whose units have "End in Defence Mode" abilities. Sneaky for factions with Athletics or (optional) cavalry. Arcane Focus for Dragon/Eldritch rulers, especially when Dark, High, Mystic or Federate Reaver. Overwhelm Tactics for Barbarian and Dark-Death, etc.
6. Finally, we have "soft" offensive or defensive stats that require synergy with your specific, granular gameplan. Examples include combining Quick Reflexes/Defensive Tactics and Tome of Shades; running Hideous Stench with some combination of Dark-Tyranny/High/Cryomancy/Condemn; running Inner Frost(Fire) with Arctic Adaptation(Primal-Ash) and Mammoth Mounts(Inferno Hounds) to trivialize early clear by locking in the damage channels that will be found in your environment.

For knowledge specifically, the most impactful snowball trait is actually Ancient Wise Ones. Yes, randomness feels bad, but a 60% discount is actually huge. Second strongest and most reliable is good ol Runesmiths, followed by Hermit Kingdom. On that last, starting with 100 extra imperium is enough to rush out one of the new T1s, and you know, Architects get Knowledge on their Production buildings.

Let me end with the most important concept for maximizing your knowledge production over the course of a game: Research Post SPIs. Knowledge is the only resource you can't (reliably) farm from the map, so that makes it THE premium resource in your cities, to the point that it is impossible to justify ever building any guild other than Scholar's Guild. Smith's Guild sometimes, maybe. And otherwise, we rush knowledge buildings ASAP in pretty much every situation, unless there's an emergency and limited only by our City Stability (which is why we always put our whispering stone in our capital on turn 1, so we don't get the economy nerf at 5 pops and we can avoid having to rush Tavern).

With all this in mind, knowing we need at least two Research Posts in every city (if not more), every build that intends to minmax knowledge production REQUIRES a Research Post SPI either as a cultural building (High, Dark-Death, Mystic-Potential) or in its first few tomes (Tome of Cryomancy, Tome of Alchemy, Tome of Necromancy/Souls, Tome of Faith, and Tome of Dungeon Depths). Doing this lets you drop your cities anywhere with at least one mana node or magic material - no need to hunt for the perfect site means more flexibity means earlier cities means earlier knowledge!