Text Leading
txt-lead
Controls the leading (or line spacing) in a multi-line text image output by the Typesetting Endpoint. txt-lead also controls line spacing for txt when txt-fit=wrap or txt-fit=wrapmax is set.
The default is 0, which corresponds to approximately 120% line height. Negative values are not allowed.
A whole number is a spacing in pixels, multiplied by dpr. A decimal from 0 to 1 inclusive is read as a fraction of the font size instead, so the spacing scales with the text.
txt-lead=10