Not something small such as a type of heel or lingerie. More along the lines of cutting her hair or losing a specific amount of weight?
Is it acceptable? Absolutely. You know what else is acceptable? Telling him “fuck no” and bolting. You’re the gatekeeper of yourself, until the day you open the gates to Hannibal.
In personal terms: girls are expected to change their appearances for me, by rational means to rational degrees. Girls are expected to change their interests for me; they learn what I like, why I like it, and ultimately become a part of it. Girls are expected to open their lives up to unprecedented scrutiny, and embrace helplessness. I have many expectations that are invasive and aggressive and manipulative.
But if someone doesn’t like my expectations? She’s not right for me. It doesn’t make her “bad” or “lazy” or “not”. It doesn’t nullify her identity as a submissive. She’s just not right for me. That’s it.
You don’t have to be what he wants unless being what he wants is all that you want.