Hi,
Guide is a bit harder to write if we don’t know what would you like to have in the end.
But XFCE lets you do whatever you want from simple stuff like wallpapers, themes, panels/docks to fine tuning panels with css or replacing default compositor with i3.
Then you could install picom, rofi, GLava, conky…
I would suggest looking for inspiration on r/unixporn or these YouTube channels LinuxScoop and diws
There is also Share Your Desktop Topic on EndeavourOS forum check it out and show us your custom desktop.