SOME really good mods worth to try:
Historical WW2 improved:
TRP, All in One
Historical WW1 improved:
Bandaid Mod 1914, 1897 Imperial Zenith.
Historical WW2 AND WW1 improved:
Blood and Iron (essentially combined and improved version of World in Flames 2 and Edge of Darkness, also contains slightly improved WW1 scenario)
Peace without Victory (you can find it on Ericafaq Facebook page; also contains improved interwar era and allows for smooth transition between WW1 and WW2 )
The Grand Campaign (also allows that transition, but it's a lot less fleshed out and poor in the interwar era content).
Other historical eras:
New World Order 2 (Cold War era).
Alt History:
The Bonaparte Legacy
Kaiserreich
For a total beginner, I recommend to play several campaigns in vanilla "Darkest Hour Full" first.
Then, Blood and Iron and TRP for immersive historical WW2 experience and PvW for the smooth transition between the end WW1 and WW2 (so far best mod for that transition in my opinion). If you want to just play short WW1 only campaign that ends ~1919, then try Bandaid Mod 1914 or Blood and Iron.
Kaiserreich and Bonaparte Legacy are good Alt History mods and NWO2 contains interesting Cold War Era scenarios.