I wouldn't do a themed name IRL, but if I did - to me, the coronation is really about the crown. Charles was king and ruler from the moment Elizabeth died, so coronation day is just the official crowning.
There are apparently a load of Yoruba names referring to a crown - mostly starting with Ade-.
Atarah and Kelilah (both f) mean crown in Hebrew.
Corona (f) means crown in Latin and Spanish (but I associate it with the beer, or the place name Corona del Mar).
Kreine (f) = Yiddish for crown.
Krunoslav (various Slavic) means "glory of the crown" - and why not Krunoslava?
The Hawaiian (f) name Lailani means heavenly wreath/garland of flowers, but is sometimes interpreted as heavenly crown.
Mongkut (m) means crown in Thai.
Stephen/Stephanie/Stefania/etc. are from the Greek name ΣτÎφανος (Stephanos) meaning "crown, wreath".
Taj (m) is apparently Arabic for crown, but I suppose it works as unisex.
Or, there's always good old Carnation.