Why can not send the RCS chats?

If you cannot send RCS chats, please check the following:
1. RCS chats require all participants in a conversation to have RCS enabled. Additionally, RCS services are provided by either Google or your mobile carrier, and availability can vary by region and carrier support;
2. Check your RCS status. Open the [Messages] APP on your device. Tap [Profile] at the upper right corner and go to [Messages settings]. Select [RCS chats] to check its availability and status;
3. Troubleshoot your RCS connection. Update Google Messages and Carrier Services from the Play Store. Ensure that Google Messages is set as your default SMS APP. If your device has dual SIM slots with both SIMs inserted, make sure your Call SIM is also set as your Data SIM. You can check this under [Settings] >> [Mobile networks].
Note:
1. Not all carriers support RCS, so please confirm with your carrier whether the service is available;
2. If you remove your SIM card without turning off RCS chats, the service can continue for up to 14 days;
3. If RCS is not working, you can try clearing the APP storage for Carrier Services and Google Messages in your device settings;
4. If the issue persists, consider turning off RCS chats through the Google Messages opt-out portal and setting it up again.