How to do wholesale sizing options just like on the screenshot

[ArtyZak]

Is there any third-party app which can handle that functionality or I can achieve that only with custom coding? 

[Shadab_dev]

So the size part is basically variants of your product so that will be possible with custom coding. I mean every theme has that but since you have a unique design you will need code customizations. But in short yeah it is possible. 

Please see a reference site below of a client for whom I added image swatches for his colour variants.

Site: www.kpsclothing.in

Please reach out via mail for a convenient conversation and collaboration.

Best 

Shadab