OpenPGP standard applications can be run through the Terminal/Command Prompt application.
https://techdocs.broadcom.com/content/dam/broadcom/techdocs/symantec-security-software/information-security/pgp-solutions/10-4-2/generated-pdfs/pgpCmdline_usersguide_en.pdf

If you are not familiar with the Terminal on Linux/macOS or the Command prompt on Windows OS, there are a few additional software you can choose from:
https://www.openpgp.org/software/