LB, I’m not sure exactly what it is you’re asking. I don’t know anyone that specifically wears a white kippah to weddings. I know many men who wear white kippot on Shabbat, so if there is a bar mitzvah on Shabbat, yes, they wear a white kippah.
If we’re attending a wedding, normally my kippah will match my shirt. I try to wear a colored dress shirt to weddings, because it’s nice to dress up in something other than a white shirt.