After it was rumored that Apple advanced its first keynote to April 20, in the mouth of Siri itself, in the end the date has been confirmed by the company itself. So We already have the first keynote of 2021 confirmed; without us knowing for sure what is going to be advertised. The renewal of the iPad Pro would be almost assured.
The range of Apple devices is usually renewed from time to time; hence an iPad family refreshment is expected in the spring, before the WWDC brings a major refresh of the catalog of devices and software. So, if the 2020 iPad Pro saw the light of day at the end of March, Apple was a little behind if it wanted to keep the annual renewal. Just over a month late, the April keynote is already confirmed.