Sadly, even though most of the immediate competitors provide sunroofs, none of Maruti cars provide sunroofs. However, the China-spec Ciaz has one.
Even though Ciaz does not have a sunroof you can go for an aftermarket solution and get one installed in your Ciaz. The process should however only be performed by an expert professional. The process would involve accessory changes, cutting, wiring, sealing which all need professional expertise.
I am not sure about the price though.