Breaking this out of a comment by @davelab6 . Flutter now support variable fonts on all platforms (web canvaskit soon), this issue is about improving support to aid in the developer experience.

So, to implement full support for variable fonts, I recommend Flutter have those 4 things:

• a way to set variable font axes values with inheritance
• by default, when the opsz axis exists in a font, set the value to the font size, and allow a ratio override, plus override via the above axis value sette. (Ideally the auto value is resolved to physical Points, 1/72nd of an inch, although I am recommending that ideal as a partisan and recognize there are other positions on what value to use; but the key idea is that it is set based on font size)
• correctly render semi-opaque text
• correctly render outline-stroked text

Originally posted by @davelab6 in #33709 (comment)

and the following comment:

• Flutter developers and end users of flutter apps will need a easy way to know what's actually available in each VF family; that's because they will often be constructing UIs for end users to set axes values, as much as they will set axes values within the apps own code itself.

Related issues: #33709

See go/default-opsz.