I'm only interested in managing English or Scottish clubs so my setup using the default database:-
English (down to tier 6), Scotland (down to tier 4) and first two divisions of Belgium, France, Germany, Italy, Netherlands, Portugal, Spain in a large database with all players based in the UK loaded, this gives roughly 75k players to start with.
When the English 10-tier league structure is out after a month or two after the game release, I'll usually pick a tier-8 club to start a LLM career.