After designing of your Canvas screen, the plugin can help you to add all rectangle, label, SVG, button, container, and circle prefixes via "ADD PREFIXES" button under Export tab.

Create a frame on Figma page, add some Figma controls, like Text, Autolayout, Ellipse, or others, and click on “ADD“ button. The plugin will generate mentioned prefixes in names of your controls.

After clicking on button, prefixes will be generated.

If you switch on “Replace RECT by HTML“ in Features under Settings tab, all rectangle controls will have html prefix instead of rect. Detail info of how to put the variable to on mode, you can read here.