This is a feature in miniExtensions Form. You'd need to install it first.

Conditional Filter for Linked Records in Airtable Form

Narrow down the options or limit the choices

Form Feature

Our miniExtensions Form has many powerful features and this is one of them. It allows you to restrict the records selection within a linked record or dynamically drill down through linked records based on certain field(s) in the linked table. For example, instead of showing a list of all cities, you can allow users to select a county first to narrow down the options, so they can find their city faster. Also, you can select multiple fields as filters.

This can also be a way to create a Dependent Drop Down List by limiting which linked records are shown depending on what users have put in another field.

💡Update
It’s now possible to prefill the filter values using the form URL so you can dynamically filter the selectable linked records. Learn more about this feature here.

Features

Filters can be shown as regular fields inside the form (like in the demo).
Filters can be hidden from the form and set only by prefilling their values in the form URL (not shown in the demo).

Demo

This form has a linked record field that you can filter. It will show a sub-category list based on the region you select:

Use Cases

This extension can be useful in a lot of scenarios. You can use it to:

Make it easier for people to find what they want.
Minimize human errors and speed up efficiency.
Restrict the options users can select from.
Limit clients to only view their own linked records.
Prefill the form URL with “filters” to force linked fields to only show limited records on the form.

If you click on the sample view below, you’ll see the table that’s used for the demo above.