How to Create Dynamically Changing Drop-Down Selection Lists

My question is about sheet 3 in the file attached.



In the column, A (for example A4) when has a value then in column E / Article Number (eg E4) has a dropdown for selection matching to column A. and to do that I have used the formula
=XLOOKUP(A7;Sheet1!$B$2:$BF$2;Sheet1!$B$3:$B$20;;0;1)



Now what I want to achieve is, in column A, say in cell A4 if I change the value then matching to that a new set of dropdown should appear in cell E4 matching the changed value in cell A4 for example. The Variant number should be populated from Sheet1!$B$2:$BF$2 and the drop-down should be matched as per sheet 1.



In short, if the user changes the Variant number in sheet 3 column A, the Article Number column E should also automatically change and give a new set of dropdown option matching the changed value of column A. Reference of values are in sheet 1.



Hopefully, I am not confusing.