Roundesk Pro plan can have only one host access whereas Roundesk Team can have two host access and Roundesk Enterprise can have three host access.
If the user is having a Team or Enterprise plan, then they can give host access to one or two users during an ongoing meeting. The user hosting the meeting will find the list of participants in a meeting as small windows below when the settings toggle is accessed. Click on the settings icon next to the user to find option to give host access to the user.