That’s not possible.
However, EventBrite.com lets you create forms for events that lock submissions after you hit X number of responses. So you could simply create your forms in EventBrite, and then have your form submissions automatically feed into Airtable using Integromat or Zapier.
To lock your form manually, you could just stop sharing the form altogether — or change the URL to a different URL so people can’t find it. If you still want them to see the form at its old URL, then just remove all the fields from your form so there are no fields to fill out anymore.
Hope this helps! If this answers your question, could you please mark this comment as the solution to your question? This will help other people who have a similar question.