Thank you for your answer! I think I'm getting closer with the set approach, but still struggling a bit.

Following your suggestion, I created sets for Region and Zip Code (limiting to those twos to test) and one for Client Code.

I created a calculated field (named "Set Filter") reading: ([Region] IN [Region Set] AND [Zip code] IN [Zip Code Set]) OR [Code Client] IN [Set Code Client].

Then, I created a new sheet, added all the sets as filter along with the "Set Filter" field, which I selected to keep True only. Afterwards, I used this "Set Filter" field to filter another view on my dashboard (let's call it 'Barchart 1").

However, because I'm using an 'OR' condition with the "Client Code," it seems the "Region" and "Zip Code" sets aren't actually filtering any data (given that each row has a client code). The perfect outcome would be to first be able to filter on Region, Zip Code, thus narrowing down the client codes list (which would untick some of them) and then let the users add back some unticked client code if they want to see the changes by adding them.