In June you will be able to see when the receiver of a chat message in a private chat saw the message you sent or not. There is also settings for this in CsTeamsMeetingPolcies and Teams Admin Center (TAC). There could be privacy issue in some countries for this feature so be sure to prepare your policies.
You might seen in the Teams Admin Center (Messaging policies) and Powershell that there is an option for Read Receipts. Here you can configure if it should be User controlled (default), Turned off for everyone or Turned on for everyone.
In Powershell run Get-CsTeamsMessagingPolicy to see your policies and check ReadReceiptsEnabledType. You can set ReadReceiptsEnabledType to UserPreference (Controlled by user), Everyone (
Turned on for everyone) or None (Turned off for everyone).