This sound more likely. There are still plenty of uses for XML, so no reason for PHP to stop supporting its creation or reading.
I’m currently working on a personal project that creates KML and GPX files, both of which are XML based file with geo-location data. I’m using PHP’s SimpleXML extension for that, which is supported in versions 5, 7 and 8 of PHP. I also use it at work to create Ecommerece product feeds for Google Merchant Centre and Facebook Shops.
I guess the site may provide data in some other form, like JSON for exapmple. Can you find out what type of data they will supply?