The Airtable "Rich Text" column type is an excellent tool to update your product descriptions. As it allows you to format the content inside cells - introducing headings, bold text, italic text, etc. - this allows you to control the exact HTML of your product descriptions right from within Airtable. With a quick little configuration change AirPower will take your formatted text, convert it to HTML, and send it off to Shopify. Here is how.
First, change the type of the column you want to sync to your products' descriptions to "Long Text". Then enable the "Enable rich text formatting" toggle. You will immediately see visual shortcuts to format your text, but you can also use the tried and true Ctrl+B, Ctrl+I, etc. shortcuts.
Second, open the AirPower config via your Shopify admin. Find the Products section, and in your column mappings find the entry for "body_html". This is the Shopify product attribute that stores your product descriptions. If you map this body_html field to the column we created in step one, then AirPower will convert your product description HTML to Airtable's "rich text" format during Shopify-to-Airtable syncs, and back to HTML during an Airtable-to-Shopify sync.