The read receipts allow other conversation or chat partners to see whether we have read one or more received messages.

This feature is similar to the blue check marks in WhatsApp Messenger and can be (de)activated on the OnePlus smartphone at any time if desired.

Android 10 | OxygenOS 10.0
Step 1:  Open the  Messages app
Step 2:  Open the  menu
Step 3:  Open the  Settings
Step 4:  Tap on  Chat features
Step 5:  Enable or disable  Send read receipts
  1. Open the Messages app
  2. Open the menu
  3. Open the Settings
  4. Tap on Chat features
  5. Enable or disable Send read receipts

OnePlus Instructions