Looking for Encryption application

Encrypto by MacPaw is a free file encryption app available for macOS and Windows. The app uses AES-256 with no configuration; provide a password for encryption and optional password hint.

Save the file to iCloud and then send the person a link to download it?

I'm not a fan of cross platform encryption tools due to the friction to set them up properly and choose them, but you could do far worse than trying signal.

• https://www.signal.org

Other notable options in the space are https://gpgtools.org and https://www.openpgp.org

But seriously, try the simplest thing that could work - iCloud - and then see if the others are worth the setup.

Consider Firefox Send:

Firefox Send lets you share files with end-to-end encryption and a link that automatically expires.

For files up to 1Gb you don't need to sign up.