Audrey,
I looked deep into it, since some of my actions would need that workflow. Not possible, however the workaround is dependent on how you identify the new records in the second table (via form).
Now you have a button that opens the url (form), create a new record. Bring the view of the second table to the first one and upon a record entering the view create automation that looks at the second connected table and triggers action to find records in the first table and populate needed fields. I use a checkmark and additional airtable field that looks at it (Last Modified Time). I based find records on recordID from the first table, which is looked up in second table and within automation those are matched.