By default, on the product page of Magento 2, there is a simple text field for quantity for products. Add increment and decrement button in Magento 2 to make easier for customers to buy a produc which can also help in boosting the sales. It can done by using Knockout JS in Magento 2. Here's a step by step guide:
Add Increment and Decrement Button in Magento 2
There is another option to show quantity increment in the frontend.
That is showing a list of quantity increment, even along with total prices, in the product page.
Here is an example when you use Magento 2 Quantity Dropdown extension:
Attachment 11369
Hope it helps
It can done by utilizing Knockout JS in Magento 2. Here's a well ordered guide: Add Increment and Decrement Button in Magento 2.