I buy mine online from dirty labs because I need fragrance free stuff, but I’ve seen scented varieties at most hardware+home goods type store (Menards, fleet farm, Home Depot, Lowe’s, etc). Haven’t really looked elsewhere, but it’s all niche brands. You’ll probably need to read the ingredients to find a good one for your needs, unless you do some looking before you go or order online. The link below has info about the available enzymes and what they are used for - most detergents I’ve seen in stores have 1-3 (of 5) of them. The stuff I get has all 5 types because I’m too lazy to sort out what stains/smells are from what.

https://caringconsumer.com/products/cleaning/laundry-detergent/enzymes/

It’s a bit (very) pricy, which is why I don’t use it every washing (some exceptions like underwear and bedding always get it), but it does a pretty good job at getting rid of the oily residue that causes “stale body” smell out of undershirts/sheets, which is very noticeable when using fragrance free detergent. And ofc that sour mildew smell.