Pega enables the collapsible menu only when the device width is between 1025 pixels and 1440 pixels. There is no OOTB way to increase this limit. If you are okay with customizations, below could be the solution.
1. pyAutoCollapseLists Section: find and replace the limit for 1440 pixels to somewhat higher value, for example to Full-HD resolution (1920 pixels).
2. py-responsive-overrides css: Copy the below two blocks into your application custom css and change the max width to Full HD (1920px)
- '@media screen and (min-width: 1025px) and (max-width: 1440px)'
- '@media screen and (min-device-width: 1025px) and (max-device-width:1440px)'
*** If screen size dips below 1025 pixels, hamburger menu appears in the portal header.