How to set up auth provider and named credentials?

In the Setup menu, search Auth. Provider in quick find box.

Give clientId, client secret and endpoint url (create project/app , then generate credentials).

Scope : refer service provider's document, and give relevant scope.

Lets consider google sheet example, visit https://console.cloud.google.com/

Create project

Fill out the mandatory fields and click Create

Click OAuthConcent Screen to create the application.

Once the authentication is done, status will be reflected into the named credential

While creating the channel, click named credential , and select from the drop down.