Selected dropdown populate another dropdown

It’s a bit complicated here. But I’m in real trouble right now.

Let me explain
I want 3 dropdowns populate by order.
unless the first it will be disabled.
– product year (product custom taxonomy)
x product brand (product custom taxonomy)
x product title (product custom post type)

* x means disabled at start.

Select the first one will enable the second one and populate taxonomy of product that have slug from the first taxonomy.

Then select the second one will enable the third one and populate products’ title. (this stage means you will get a product that have two taxonomies related)

Then select the third one will get product value inside “in the same page”

I just want some keywords from the third one’s contents to do something next.

How can I accomplish this?
Any help would be much appreciated