By default, your Windows laptop's screen will be mirrored on the room's screen. If you prefer to have the room's screen be a second monitor for your laptop (which enables Microsoft PowerPoint's Presentation Mode with separate speaker's notes):
See also https://support.microsoft.com/en-us/windows/how-to-use-multiple-monitors-in-windows-329c6962-5a4d-b481-7baa-bec9671f728a