How can I adjust quantity fields with buttons using liquid code?

[Stevenrylski]

As you can see in the photo, I have buttons and a quantity field. I would now like to have it so that when I click on “6 bottles”, for example, I also have a 6 in the quantity field and the same for 12. How is this possible? Can I do this in the editing window with costum liquid code or do I have to go to the code view and if so does anyone have any ideas what I have to use to make this work?

First photo as it is.
Second as I want it.

[Mr_RaviRaj]

@Stevenrylski

You can Add this features by the custom code,

You need to hire a developer or Get help from developer.

Thank you