Can a Host unmute a participant automatically?

Due to privacy and security reasons, the host now cannot unmute other participants without their consent. 

Zoom now offers a  Request permission to unmute participants feature.
Once enabled for the meeting, student see the message to Allow the host to unmute them automatically at the start of the meeting. 



For the rest of the meeting, the host can unmute a student immediately without waiting for the student to accept to unmute. Student will not see the option to Stay Muted.
This feature may be useful in a tutorial session, small class setting or online quiz proctoring.

Two parts to this. You first need to enable the feature for your account and then to enable the feature when you schedule a meeting.

Enable pre-approved consent to unmute feature for your account

1. Sign in to the NUS Zoom web portal.
2. In the navigation menu, click Settings.
3. In the Meeting tab, navigate to the Request permission to unmute option (under the In Meeting (Advanced) section) and verify that the setting is enabled

Using pre-approved consent to be unmute

1. Schedule a meeting.
2. Under Meeting Options, check the Request permission to unmute participants option.
3. When the meeting starts, participants will be prompted to provide consent to be unmuted by the host:
    
   
   

Note: Once consent has been given to a host, any future meetings with this host and this setting enabled will have the same pre-approved consent. Meetings without this setting will require the host to ask each participant to unmute themselves. 

If the participants doesn't provide consent, you will see the regular Ask to Unmute / Mute options in the participants list.

Guide: https://support.zoom.us/hc/en-us/articles/203435537-Muting-and-unmuting-participants-in-a-meeting