Yast 2 ->Fonts:
Font antialiasing On
Font Autohinting On
By default, the xcb system will actually ignore the subpixel settings, regardless of whether or not you set them.
Freetype has the support built in, but not turned on for patent reasons. openSUSE has the patch file setup to turn it on, but that patch isn’t included by default (for I assume the same patent reasons). So, if one actually wants subpixel rendering, you’d have to either compile it yourself or pick a repo with it enabled.
Adding repo with subpixel font rendering enabled:
zypper ar http://download.opensuse.org/repositories/home:/namtrac:/subpixel/openSUSE_Leap_42.2/ subpixel_font
zypper in freetype libfreetype6