The description on the iTunes Store page is carried in the 'itunes:summary' tag in the top section of the feed. Where individual episodes are concerned that appears when you click the 'i' at the end of the line (the subtitle) when subscribing in iTunes. The easiest way to do what you want in those is to write your summary in a plain text editor such as TextEdit on a Mac, putting in double line returns using the 'return' key after each paragraph, then copy that into your feed entry. This will then be maintained in iTunes (unless Podbean interferes with it).
I've not tried this with the description in the Store page, but it may work there. However, the space available is rather limited and if your description is too long it will be truncated.
What you don't want to do is to put html tags such as <br> in your descriptions, as these are likely to be displayed rather than rendered in iTunes.