One of the somewhat delightful things I’ve learned as an adult is - you can just ask people for anything, and they’ll do it, much more often than you might think.
My mind was blown and my life changed forever. Now I order french onion soup without the onions (high end steakhouses are happy to strain it), shrimp tempura rolls with no tails, whatever. I order my salmon nigiri with no skin. I’ll order sides of sauces from other menu items I didn’t get.
It’s rare they don’t accommodate me. (Before you ask, I always tip super well and don’t ever mind an upcharge for a special side sauce or whatever.)
Unless it's a place with a certain vision/theme/morals or artsy food, they just want to make you happy.