Verizon customers that had Pixel 3s has the ability to use RCS through Android Messages with other Pixel 3 users. This was a legit setup, not the hack that is floating around the internet. However, Verizon does not support this with the Pixel 4 at this time.
I was running into a problem after upgrading from my Pixel 3 to 4 that if I enabled WiFi calling on my Pixel 4 it would not send text messages. After many calls with tech support to no avail, replacing my phone with a new Pixel 4 which did not solve the problem, was able to finally determine the issue was related to RCS being enabled on my account w/ Verizon. Once I mentioned to the Level 2 Tech that I thought this might be the problem, they saw where it was setup as a feature on my account in their system. They removed it and now I am able to send text messages again with WiFi calling enabled. Just a heads up for anyone that might run into this problem if they have upgraded from a Pixel 3 to a Pixel 4 on Verizon.