I have a
checkout_onepage_success.xml file in the view/frontend/layout directory of my module but changing the layout attribute of the
<page> tag from
layout="2columns-right" does not change the layout of the page.
Other updates in the file work fine, I can add, modify and remove blocks as normal but the page layout will not change. If I remove the
layout="1column" from the core
module-checkout module, leaving it with no declared layout, my layout update then DOES work and the page is 2cols-right.
Attempted to solve this by
<sequence>ing my module after the core
module-checkout but it looks like the core layout is still being processed after mine and taking precedence.