\defaultfontfeatures[jetbrainscode-thin]
   {Extension=.otf,
    UprightFont=JetBrainsMono-Thin,
    ItalicFont=JetBrainsMono-ThinItalic,
    BoldFont=JetBrainsMono-Regular,
    BoldItalicFont=JetBrainsMono-Italic,
    Contextuals=Alternate
}