How to switch Orientation on PC platform like on mobile platform,

Unity Version:2021.2 PC:window10
I designed a scene 10801920, which is usually used in portrait displays, as shown below


Now I want to use it in a landscape 1920
1080 display PC, as shown below

What should I do? The premise is that I can’t modify the UI already done. I want to get the same effect as the mobile platform. How can I achieve this on the Pc platform,

upup@@@@@@