Target dropdowns with required attribute? <select required>

[CowCow]

I apologise if I'm posting this twice. I already submitted the question but I couldn't find it so I think it didnt work.

I would like to set all Select dropdowns with required attribute to the first value.

e.g.
<select required>
<option>A</option>
<option>B</option>
<option>C</option>
</select>


I can do this easily for just any Select, by using a Form Field rule

Type= Select
Name= blank
Value= 0

But how can I target only required Select? In css I can do "select:required", so I tried that in Autofill

Type= Select
Name= :required
Value= 0

However this doesn't seem to work. Some of my required Select have a value, some don't. I think the ":required" is not appropriate for Autofill rules.

How can I do it?