This is not a 3rd party app install or sideloaded app. Just pure configuration to trick the app to open hidden developer menu.
1. First update the Samsung Internet App to the latest version.
2. Type internet://debug on the search bar, then you can access the debug option page above
3. Click right 3 dot menu and go to settings
4. You can see the bottom showing Debug Settings
6. In Main view settings toggle on Enable New GUI
7. Close the app in recent menu or force stop in settings and reopen. Then the above pop-up will triggered. Select Try New Style
8. All done, enjoy new theme of oneui 8
Video Tutorial Below
