Access Group Requirement:

A user (Who need to manage and create promotion for other users) Must Belong Manager Promotion Group To Use This Feature. Other Users Can Belong to Employee Promotion Group To Read Only

Go to Sale order -> Products -> Product Quantity Promotion

Choose Free Product Promotion

lets you define a quantity range (from–to) and the number of free items that will be added when the user clicks the 'Apply Promotion' button.

Choose Discount Promotion

lets you define a quantity range (from–to) and the discount percentage that will be applied when the user clicks the 'Apply Promotion' button.

Choose Free Product X Promotion

lets you define a fixed quantity with free items that scale on multiples. This type of promotion overrides any other promotions.

Click Apply Promotion

All promotions are applied manually by clicking the Apply Promotion button inside the sales order