A pretty cool mod that allows you to resolve your Crusader Kings battles inside Total War Attila. There are options to adjust the size of units.
The only problem is that it closes CK3 and launch it back after the battle. And initializing CK3 takes a very long time.




There is also a Mount & Blade Bannerlord mod that does the same thing but with Bannerlord but I haven't tried it https://crusaderblade.itch.io/crusaderblade