A quick entry.
1. Download a desired icon theme from https://www.gnome-look.org/, I’m going to use Qogir icon theme
2. Uncompress the file and move the theme folders to /usr/share/icons, select the folders that contains index.theme file, then update the icon cache:
$ tar -xf 01-Qogir.tar.xz $ sudo mv Qogir* /usr/share/icons $ sudo gtk-update-icon-cache -q /usr/share/icons/Qogir $ sudo gtk-update-icon-cache -q /usr/share/icons/Qogir-dark
3. Open gnome tweaks and select the icon theme to apply it.
An important advivice, other tutorials recomends copy the icon themes to ~/.icons folder but if you choose this theme some icons don’t be charged by the system. For example, in my music player the prev/next buttons don’t appear:
Is needed to move the icon themes to /usr/share/icons and update the cache.
See ya! =)