Here’s how to create a custom checkout page:
1. Go to WordPress Dashboard.

2. Select ProductX, then Go to WooCommerce Builder.

3. Select Add checkout. Select Start from scratch (if you want to make it from scratch) or Import a template (if you want a premade template).

4. Name your Template, click the icon (toggle block inserter), and then add the desired Blocks to complete your checkout page. Now hit Publish.

And you have successfully created your custom checkout page.