I have many RSS Feeds, can I make the most important ones standout by changing them to use a different color?

Yes, we have a set of pre-defined color themes that are optimized for use in both Light and Dark Themes. If you subscribe to Tapestry Premium you have the ability to assign feeds to use the colors that suit you best. 

First, Launch Tapestry app

Go to Settings > Your Feeds > "Select a Feed from the list" > Color > Pick a pre-defined color theme

After selecting the color, make sure to tap Save at the top of the screen to confirm the change.