We don’t have this natively in Stacker at the moment. But there are some workarounds.To add rich text to your app:
Enable rich text for your long text field in Airtable. This will allow you to add formatted text directly in AT that will be rendered in Stacker.
When you enter edit mode in Stacker, you will be able to edit the text using markdown.
You can also add rich text directly in Stacker using markdown, more on this here:
You can also vote for a rich text editor in Stacker here: