Here are 2 challenges you can try:
Negreira case with Barcelona:
Barcelona have been relegated to the 2nd division of Spain.
They are forced to release or sell or players above 80 OVR and you get no money from their sale.
They are banned from making transfers for 3 seasons, banned from uefa competitions for 3 seasons.
Heavily restricted wage budget limited to 800k for everything including players, coaches, scouts, until they win the UCL making it difficult on prioritising signing coaches, youth academy players, scouts or players in general.
You cant sign players from the big clubs who have a higher chance of winning the ucl or their respective league (Madrid, atleti, man city, arsenal, Liverpool, psg, etc..)
You get 5 seasons to get back to first division and stay there without being relegated back down, you get 2 seasons after the bans are lifted to try and win the ucl, if you cant you start over or you fail the challenge.
2nd challenge:
Paris FC.
This is a challenge to end your neighbors dominance over French football and UCL. You ultimate goal is to beat out PSG at least 10 times, win more trophies than them and ultimately dominate France and win the league title and UCL.
This is a tough challenge PSG have basically unlimited money, they have luis enrique and they are considered the best team after winning the treble last season. You cannot sign players from their team unless you start winning against them and prove you are better (why on earth would their players leave at least a guaranteed trophy or 2 every season and join your club), same thing applies to big clubs unless you start proving yourself.
Hope you enjoy these challenges.