My gf connected her iPad Pro (2018) to my Dell U2412M monitor with DisplayPort input via this this USB-C to DisplayPort cable. It works, and in apps that support eternal displays, such as ProCreate, ...
UPDATE: This article from 2019 is obsolete now that iPadOS 16.2 includes full support for external displays. Dramatic changes in the iPad Pro line make it reasonable for the average user to consider ...