So I assume you just installed offline.
Recoll should work under XFCE as it did with me under KDE. Try have a look at Make Dolphin Use Recoll "kio_recoll" Installed
I know, I am on KDE, but I do not see why not on XFCE. I am not expert with Thunar but probably you can work out something as I did to search by content from the file manager as I did there.
(And just in case you changed your mind and reinstalled EndeavourOS with KDE online)
I hope this helps.