Dropbox is a popular cloud-based storage system and allows for larger files such as images, videos and the like to be uploaded on the cloud without taking up space on your local storage system.
Another good feature is that instead of attaching big attachments to emails (which may exceed quota restrictions and thus be rejected from sending) a Dropbox user can insert a direct link (URL) in the email and the recipient can click on the link and download the file directly.
The helpful article by Windows Report covers how to setup and use it on Windows 11 and is worth reading..