That's not natively possible with Airtable forms. You could do it with a bunch of workarounds (i.e. adding a bunch of numerous conditional fields on the form, and then the form gets submitted into a temporary table, and then you have an automation that moves all the data from the temporary table into the real tables).
An alternative approach is to use Airtable's Interface Designer to create a tailored bulk record editing experience for your submitters. This would allow them to submit/edit multiple entries at once. The downside is that your users of this will incur a paid Airtable license depending on your plan, unlike with the shared form view.