How to add additional product at a special price to your order?

Hello guys ,

Here is my story - we have an online shop for kid toys (https://startoys.bg) which was created a couple of months ago by a professional web designer and we are about to start our first marketing campaign. I was advised by our marketer to add an additional pop-up at the checkout page or if the client "is thinking" for more than a couple of minutes for a particular product, and set an option in this pop-up to add another product to the order at a very special price (for example - with 70% off). This way, we would like to urge the client to buy two products.

I am a complete newbie but I want to learn how to do that myself. If you have any suggestions, I would be more than grateful to share them with me. I hope you understood what I am talking about . I remain at your disposal for any questions and thank you for your help in advance!

Greetings,
Stela

Adding a popup on checkout is not a good user experience, it will distract the customer from purchasing. You can see all the website has removed all the obstacles from the cart and checkout page to make the user journey more easy and
I suggest you think again and make adjustments to the popup concept on the checkout page.

Popup is often difficult to close.
Whenever I saw popup, I always find myself subconsciously closing the entire browser tab by tapping the back button.

Thank you for your replies, guys. Do you have any suggestions then on how I can tempt the client to add another product to the order as well? One at a special price of 70%. It seems like a good idea to sell two products at once even though the second is with small or no profit.

There is a product option feature, where you can add option name (Buy it with), product image, name with normal price.
Then you can add a lower option additional price to the product.