The font-optical-sizing property
The font-optical-sizing CSS property is a very fine-touch property. It takes only two values:
auto as default. The auto setting allows browsers to modify a font’s characters to suite the font size and pixel density.
The standard mentions the opsz font variation being used for this purpose for OpenType and TrueType fonts. This axis allows the font to deviate at different font sizes. For example, at smaller font-sizes, the characters might have thicker lines to improve readability.
The font-optical-sizing CSS property was enabled by default in the 10 Dec 2019 Chrome 79 release and the 5 Sept 2018 Firefox 62 release.