Since I only play PVP, I can only give you an answer from this aspect. If you're not good at making changes to the whole structure, take out a winger. Whatever the formation, taking out a winger has the least impact. If you want to go a step further, you can take the remaining winger back and make changes to the defensive midfield combination and the role selection of full-backs. With good adjustment, you may not even feel the impact.
The core of FM24's top tactics should be the DM-S+DM-S combination, which is more stable and has a higher limit than other defensive midfielders, which I have experienced especially in online games. This tactic is also the one I use most in online matches.
Are underlaps still an optional part of this tactic?
Since I only play PVP, I can only give you an answer from this aspect. If you're not good at making changes to the whole structure, take out a winger. Whatever the formation, taking out a winger has the least impact. If you want to go a step further, you can take the remaining winger back and make changes to the defensive midfield combination and the role selection of full-backs. With good adjustment, you may not even feel the impact.