Please see my comment here:
As it is currently, Zorin OS Lite themes still exist and can be used. From the Settings application > Appearance
Select a Zorin OS theme
The layouts should also be present in the settings app. Be warned, if you select a different layout - all custom configurations for your desktop layout will be utterly wiped out.
Changing the Wallpaper is easily done by right clicking an open area on the desktop screen and clicking Desktop Settings > Background.
On XFCE, if using more than one monitor, XFCE supports having a different wallpaper on different monitors, unlike Gnome. So you can perform this action on each monitor. Right click on open area of the desktop on that monitor.
Browsers: In most browser settings, Including Brave or Firefox, select Use system titlebars and borders and Use GTK