Here you go, here are two example queries querying an xml structure that has a namespace. The first query will actually include some auto generated prefixes by SQL, but the second query doesn't:

DECLARE @xml XML

SET @xml = '

<XML xmlns="https://temp.../test.xsd">

<Content>

<Data>

<Node1>1</Node1>

<Node2>2</Node2>

</Data>

<Data>

<Node1>1</Node1>

<Node2>2</Node2>

</Data>

</Content>

</XML>'

--using WITH XMLNAMESPACES

;WITH XMLNAMESPACES(DEFAULT 'https://temp.../test.xsd')

SELECT @xml.query('//Content')

--OR to return xml without the p1 prefixes:

SELECT @xml.query(

'declare default element namespace "https://temp.../test.xsd";

//Content')