lead oxide and HCL

Reaction does occur.
PhO(s) +2HCl(aq) ---------> PhCl2(aq) + H2O (l)
Since PhO is a base when it is put together with an acid, neautralization occurs when they are in a correct ratio.
For example, when there is one mole of PhO, two moles of HCl must be present in order to react completely.
During the reaction, a salt (PhCl2) Lead (II) chloride and water (H2O) are produced as the only products.

coating effect occurs.
the reaction is incomplete

No, protective layer PbCl2(s) would be formed which prevents PbO from further react with HCl.

The chemical symbol of lead is Pb, but not Ph.