add end-to-end encryption for your iCloud backups, for instance. However, prior to uploading the associated files, it is advisable to encrypt them yourself locally with a security tool.
Consider it like this. You may have a deadbolt on the main entrance to your home, but adding a chain or a latch at the top enhances security even further. That additional lock is similar to the personal encryption you would implement before uploading data. If someone attempts to force open the door with just a deadbolt secured, it might give way, but with added locks providing reinforcement, that brute force effort is less likely to succeed.