Ok, it was easy (on my Lisa)
I installed Google Messages app, grant it permissions it asked for, but then also went to Settings, Apps, Messages app and grant it other Permissions and Notifications.
And set it as my now a new default app for SMS
At first it told me that I don't have SIM card supporting RCS. But after a minute it notified me that it was started to set RCS For me and asked me to confirm my Google account and phone number
Then I opened Chats, checked which of my contacts support RCS messaging and started a RCS chat
For contacts who don't support RCS on their side, messages will go the old way by SMS
RCS (Reach Communication Services) turn the old SMS messaging to the messaging experience like in WhatsApp. You can set groups, see when the other side is typing, you can send media and chat goes over WiFi (where available) and not counted on your prepaid or postpay account