Hey Tarun,
Below is the sample code.Could you please try by making changes as you require.
<xs:element name="DateOfBirth">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:
pattern value="\d{2}[/]\d{2}[/]\d{4}"/> for DD/MM/YYYY format. (\d{4}[-]\d{2}[-]\d{2} for YYYY-MM-DD format)
<xs:length value="10"/>
</xs:restriction>
</xs:simpleType>
</xs:element>