I suppose making gangs akin to the nemisis confrontation event would be easy to implement, have them move together in packs of 3-5.
A mod or update to add higher difficulty guards would be nice as well, which could be implemented by giving guards better equipment and armor based on their rank, which is currently flavor text.
Another solution I thought of for making combat more difficult is allowing enemies to get their own perks as well (since fighting them levels them up according to what level you are at), even making the perks match their personality. Like, bdsm enjoyers would probably have the perks to make binding you easier, bullies would have the shove and weapon perks, guards would have the armored perk as well as one or two sexual perks according to their preference. The perk system that applies to what the player likes can be retrofitted to apply to the other characters as well
