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')