The configuration of your site's checkout page is done through the admin panel: "Configuration" - "Design" - template design settings - "Checkout" section.
You have the opportunity to change the position of certain blocks in the checkout of your site, for this, in the admin panel, you need to click on the “three dots” icon and, holding it down, move the block to the place you need, up or down, and the blocks in the checkout will take the appropriate place place according to the admin panel. You also have the option to disable/enable this block for display in the checkout and also manage the functionality, if you click on the "pencil" icon, a panel with the available functionality of this section will open.
A template is a ready-made layout that you can customize yourself, in a pre-developed professional design. Which already takes into account all the requirements for the decoration of store sites.