Unlike most parts of your store, the checkout page is controlled by Shopify — not the theme. That means there are limitations to what you can change unless you're on Shopify Plus.
But don’t worry — here’s what you can customize (and how!) ✅
Basic checkout customization
Standard checkout customizations are available on all pages for businesses that are on the Basic plan or higher. Advanced checkout customization features are available only on the Shopify Plus plan.
Steps:
Go to your Shopify Admin > Settings > Checkout.
Iin the Configurations section, click Customize to open the checkout editor.
Make your changes (logo, colors, fonts, etc.).
Click Save
You can customize these parts of your checkout even if you're not on Shopify Plus: