No

In no namespace, the language attribute specifies the primary language for the element's contents and for any of the element's attributes that contain text.

Its value must be:

• a valid BCP 47 language tag,
• or the empty string (unknown primary language)

The lang attribute is a global attributes.

Xml

The lang attribute is also defined in the XML namespace.

The lang attribute in the XML namespace xml:lang may be used:

• on HTML elements in XML documents,
• as well as elements in other namespaces if the relevant specifications allow it.

The following specifications allow lang attributes in the XML namespace to be specified on their elements).

• MathML
• SVG