You can use expanded record view to edit existing data - which is essentially a form. However, I expect you are talking about web forms?
If this is the case then, in common with many similar platforms, you can’t provide record editing through forms published online. However it’s possible to capture new records into a table this way - which can link to an existing record (but this would mean the person entering the data would have to see the look up table value which may be a security issue). If this is all you need then you can have the additional fields in a seperate table with a join to the main one.
But, if you want to update information in the main table then you need a way to take data from the table to which the form enters it and then move it to the table you want to update. Unfortunately, there are no tools in Airtable to do this - but it can be done with Zapier (which I find an essential partner to Airtable - it really brings it alive).
The downside is that Zaps with Airtable are not (currently) Instant and so you have to wait until they run (5 or 15 minutes depending upon your Zapier account) and you need a paid Zapier account as they need to be multi step Zaps.
Hopefully, soon, Airtable will implement Webhooks (and Instant Zaps) which will enable Zaps to run immediately - this would hugely improve the platforms capabilities in my opinion!