flutter_svg/example/assets/simple/style_attr.svg

<svg xmlns="http://www.w3.org/2000/svg" fill-rule="evenodd" viewBox="0 0 25 25">
    <path 
      d="m10 10 L 20 20 L 10 20z" 
      style="stroke-linecap:round;stroke-width:3;fill:#767676;fill-rule:nonzero;stroke:rgb(0, 60, 60);stroke-opacity:.2" 
    />
</svg>