Procedure
- Navigate to All > System Definition > Choice Lists.
- Search for the table sc_cart_item and the element quantity. The existing quantity choices appear.
- Add quantity choices, modeling them after the existing ones.
To reduce the quantities available for catalog items, delete the relevant quantity records. For example, to reduce the quantity range to 1-3, delete the records for 4 and 5.
To restrict the roles allowed to change quantities, edit the List of roles (comma-separated) that can use the quantity selector in the shopping cart (glide.sc.allow.quantity) service catalog property. For example, you can limit this ability to the admin and catalog_admin roles.
Feel free to mark correct, if your issue has been resolved, so it ends up in solved queue.Will be helpful for others looking for the similar query.