The co-host feature of Zoom allows you to provide another presenter, such as a guest speaker or another instructor, the ability to unmute themselves and to share their screen.
This is not recommended for student presentations.
You can make another participant a co-host in your meeting by using the Participants window.
Open the Participants window
Click Participants to open the Participants window.
Open the More menu
Hover over the name of the participant who is going to be a co-host, and choose More.
Select Make Co-Host
Select Make co-host from the menu.
After a participant has been made a co-host they will be able to unmute themselves and share their screen. They will also have access to the co-host controls.