Variable Font Playground
Font
Source Serif 4Optical Sizing
fontOpticalSizing:
none
none
Variable
fontOpticalSizing:
auto
auto
Variable
fontOpticalSizing:
16
Variable
Other Variation Axis
There are two types of variation axes in variable fonts: registered axes and custom axes. Registered axes include five variations: wght, wdth, opsz, ital, and slnt, while custom axes are defined by the font designer.
Source Serif 4 has 2 variations Optical Sizing(opsz) and Wight(wght)