2018 11” IPad Pro

Apple describes vintage and obsolete products here.

Obtaining service for your Apple product after an expired warranty - Apple Support

As to when support for your iPad will be lost, nobody other than Apple will be able to tell you; Apple does not pre-announce end-of-life for its devices. At this time, all models of iPad Pro remain in support.

For the most part, history to date demonstrates that most iPad models receive five to seven [or more] years of mainstream update and hardware support.