Audacious can use old Winamp skins
And you can find thousands of them in the Winamp Skin Museum
Skins should be placed in ~/.local/share/audacious/Skins/
BTW. I changed audacious to audacious-gtk3
(The gtk3 version doesn’t show three buttons on the taskbar)
yay -S audacious-gtk3 audacious-plugins-gtk3