In short: there is no in-game model reflection for being any kind of multi-racial character, no.

We know, in lore, that at least Hyur-Elezen and now Hyur-Ra are possible; it seems likely that Hyur-Miqo'te should also be possible (given the relative compatibility of body sizes) but it's never been addressed directly. Hyur-Roegadyn should also be somewhat possible, though it's unaddressed and this is a case where there may be a question of birth weight and in-utero development. Compatibility of any other Spoken with Lalafells is, unsurprisingly, left completely unaddressed. So if you want to say that your character is a half-Elezen like Hilda and you just note to compatriots that ear options for your game model are limited, you'd still be perfectly within the bounds of the lore.

(It's also relatively safe to assume that the various examples of Hyur compatibility above are also compatible with each other for the same reason.)

Anything more "exotic" than this, however? No. There is, currently, no lore basis for it, and if you are trying to RP in the bounds of the established XIV lore, there's no example for it.