Using Indirect with Dynamic Header Name

Try

Then press Control+Shift+F3 in the selected table you will get a window called create name from selection ->>> check mark only top row then ok

now press in A1 cell Alt->A->V->V in setting tab at allow list select list. The in source put =INDIRECT($A$3) and then ok.

This is the way to create a dependent drop down list.

Check the attached file.

Hope this will help you.