For the cart page, merchants can add any section that is listed in the Theme sections. Nevertheless, there is a section designed specifically for the cart page.
Steps
In the theme editor (Customize), open the template selector
Select Cart
On the left-side bar, select Cart template.
Make necessary changes > Save.
Show cart note: allow users to add any additional for the store to check before shipping out.
Show discount code: provide any special promotion coupon
Show estimate shipping rates: users enter their address to determine the shipping fee.