You can make changes to multiple episodes at once inside a feed.
Actions you can take:
Set all to published/scheduled
They'll automatically be set to "scheduled" if their publish date is in the future
Set all to unpublished
Delete episodes
Copy episodes to another feed
Change the show notes for all episodes
This replaces any content that is currently in the show notes
This can be rich text by highlighting your text and adding formatting, e.g. links, bold, bullet points, etc.