XCOM 2 had great mod support coming out of the gate (something I wish could be said about Civ 6), and I played with mods that made the game easier and less frustrating. For example, there's mods that tell you what you can see from a tile without moving there (which enemies you can shoot at, is it a flank, can you not see but still have squadsight, can you hack the objective, etc.). I also played with true concealment so that the timer doesn't tick down as long as I'm still in concealment, allowing me to plan my approach and how to break concealment. Instead of, say, running headlong toward the objective because that's all you have time for and then get caught by enemy patrols.
I'm only about a month and a half into my Long War 2 campaign (on Beginner because the original Long War has a reputation). I think the most interesting new mechanic is infiltration. It serves a purpose sorta similar to fatigue in the original LW in that both prevent players from just running the same squad on every mission. The way infiltration works is that, when a mission is generated, the player is told how many days and hours until the mission must launch. The player then selects who goes on the mission and how to outfit them. More people = longer infiltration. Bulkier weapons = longer infiltration.
Players can launch a mission before it reaches 100% infiltration, in which case advent is more suspicious and the map starts with more enemies. Or the player can spend more time to try to reduce the enemy presence, but that means tying up some of your limited number of soldiers.
Because soldiers can only infiltrate one mission at a time, and the player will be aware of several missions at once, the player has to pick between missions (weighing mission rewards and difficulty) and juggle different squads working on their own missions. The different squads also meshes well with the LW2 officer mechanic, where soldiers can buffs for going on many missions with the same officer.
The other thing to know about LW2 is that stealth missions are now a thing. Not just a thing, but sometimes necessary. In vanilla XCOM 2, players will generally clear every map, and tactics are manage how many advent you have to deal with at simultaneously. In LW2, sometimes the player may get an important mission but with a very short infiltration time. You can check out YouTube videos (I've been watching xwynns) where people go in with a shinobi scout and maybe a specialist for remote hacking. Run around advent patrols, hope you aren't spotted by drones, get to the objective, and run (or wait) for extraction. Like a real guerrilla organization going up against an enemy with a huge material advantage.