curl supports the SCP and SFTP protocols if built with a prerequisite 3rd party library: libssh2, libssh or wolfSSH.
SCP and SFTP are both protocols that are built on top of SSH, a secure and encrypted data protocol that is similar to TLS but differs in a few important ways. For example, SSH does not use certificates of any sort but instead it uses public and private keys. Both SSH and TLS provide strong crypto and secure transfers when used correctly.
The SCP protocol is generally considered to be the black sheep of the two since it is not portable and usually only works between Unix systems.