Photoshop Elements offers a good and reliable solution to "backup" both your catalog and photo files. The result is a 'catalog folder' containing everything to restore on the same location (drive and path) or in any new location (drive, partition, master folder). That catalog folder is generally generated on an external USB drive.
You can create that backup folder directly on an external drive, but also to a network. If you have a Cloud solution with enough space available, you can also copy that backup folder to the Cloud via your operating system.
As Elements does not offer enough space for a backup (the Cloud space in PSE2021 is very limited), you'll depend on other solutions like OneDrive, Google Drive, Dropbox, Amazon or similar. Those solutions are either paying or somewhat limited.
However, some of them (I use OneDrive and Dropbox) offer a practical way to perform those backups. The principle is to have a synchronized duplication of your photo library (the photo files) between the Cloud and a special system folder. Those services automatically manage the syncing. For the catalog itself (the database), I don't manage it in the system folder but I can store copies as backups. Of course, if you have enough cloud space, you can create a 'backup folder' directly in the system folder and it will be automatically synced to the Cloud, but that takes a lot of time.
Those solutions are good for backups, but they require the duplication on both the computer and the Cloud.