Do you have this in red?
'Rosso' — double 's' means a longer, sharper 's' sound: 'ROS-so'. Don't rush through it.
When you like a style but want a different colour. Point to the item while asking to make communication clearer.
'Ha' is formal 'avere' (to have), addressing the staff member as Lei. 'Questo' (this) refers to the item you're holding or pointing to.
Ce l'avete in blu?
Do you have it in blue?
Using plural 'voi' — for chain stores with multiple staff
Esiste in altri colori?
Does it come in other colours?
Open question to see all available colours
Avete qualcosa di simile in verde?
Do you have something similar in green?
When the exact item isn't available
Italian fashion uses very specific colour names — 'bordeaux', 'tortora' (dove grey), 'ottanio' (teal), 'cammello' (camel). Learning these makes colour conversations much easier.