Classic and modern SharePoint sites, lists, pages, and libraries can be programmatically updated using a variety of methods. You can use tools such as the Patterns and Practices API, Office 365 CLI, and Microsoft Graph to manipulate built-in properties and fields, or you can introduce new components and client-side scripting with the SharePoint Framework and SharePoint Framework Extensions.

Application packages that are developed using SharePoint Framework can be deployed to sites using the SharePoint App Catalog.