The purpose of one-page checkout is to gather the information that is needed and complete the sale as quickly as possible without requiring extra clicks for the shopper. When one-page checkout is enabled, the entire checkout process takes place on a single page. Each section of the checkout information is expanded as needed.
One-page checkout is enabled by default. If you are implementing a custom integration or checkout extension, it might be necessary to disable one-page Checkout.
To disable one-page checkout:
On the Admin sidebar, go to Stores > Settings > Configuration.
On the left panel, expand Sales and choose Checkout.
Expand the Checkout Options section.
For a detailed description of each of these configuration settings, see Checkout Options in the Configuration Reference Guide.
If the setting is for a specific store view, choose the store view where the configuration applies.
When prompted, click OK to continue.
Set Enable Onepage Checkout to
If necessary, clear the Use system value checkbox to change this setting.
Click Save Config.