Read the release notes, which are also attached to the announcement:
New Feature – Plug-in UI scaling
You can adjust the size of the user interface from -50% to +100% in 12.5% increments. This allows you to scale the UI on native 4K monitors for better readability, for example. When using HALion/HALion Sonic in Cubase/Nuendo, the available maximum and minimum scaling factors depend on the UI Scaling value that is set for the host application. For example, if UI Scaling is set to +50% in Cubase, the plug-in can only add a maximum of +50%.
NOTE: When using Cubase 15 and higher, UI Scaling must be applied via the Function menu, which is located in the HALion/ HALion Sonic plug-in header. In this case, the Options page only displays the set UI Scaling value.
New Feature: Standalone UI Scaling
The UI Scaling option on the General page of the Plug-in Preferences dialog allows you to set the UI scaling for the standalone application. The range is the same as for the plug-in, see above.