Opening the widget option panel gives you the option to change the letter spacing, arrow size, arrow thickness, and icon color. You can also specify the separator line color when the dropdown is open.
for information on finding your Product ID.
Your option name must match the option name in Shopify exactly. It is case sensitive, so if your option name is 'Size' in Shopify, it must also be 'Size' in Muse.
Fill & Stroke
You can customize the fill and stroke color. You can also add rounded corners.
You can set the Item Variations to responsive width. You can also change the width and height.
Style the font through the text panel. Change the typeface, font color, etc.