Clearance Requirment for 2SC0115T base board and Affect of Conformal Coating

Hope everyone is doing well. I am actually designing a base board for the 2SC0115T and I am struggling with the clearance requirements. Actually I have some board constraints to cover clearance requirement. My question is: " Does the Conformal Coating affect the Clearance requirements? Like If I design it for the lower voltage requirement. Can I run it for the 800VDC for example, in case I do a conformal coating on it? I searched on internet and different IEC standard. I couldn't find info on the affect of the Conformal coating on the clearance. Does the IEC standard accept that? If not? why?