There are only 2 outfits included for the combat animations (Peasant Farmer and Forester). I recommend you reach out to another artist and hire them to draw you some custom outfits for the animations you need.
If I purchase your product, is it okay if I customize the character animation sprites inside and use it myself?
Yes, of course, you can make any changes you like 👍
For more information, you can read the user license linked at the bottom of the page.
