Unless you’re playing one of the two new game modes brought into FIFA 20. No rules, or survival. The maximum number of red cards you can get is 4. Once you receive a fifth red card, which would end up in you having less than 7 players on the pitch the game will stop and your opponent will receive an automatic 3-0 win.
Is it worth it?
Probably not because ultimately no matter how angry you get, to get than many players sent off. Your the only one losing out and you’ll end up not being able to use those players as they will be suspended for the next game.
Unless however, you are playing regular online seasons or offline kick off mode where the red cards don’t count.
It’s also worth mentioning that red cards do not count in FUT draft. So if you’re in the 90th minute and you”re opponent is running clear through on goal and you’re drawing then you may as well take him out and get a red card as you won’t be impacted in the next game.