As other modern web browsers, Opera also uses user agent as an identifier for web servers. Normally, if you use Opera running on Windows 10, web servers will identify your browser as Opera on Windows 10 and will serve web pages according to the platform it belongs to, desktop in this case.
For a certain reason, you might want to change the user agent of your Opera browser. But first, you might want to view the user agent of Opera to figure out what it looks like. Following is the example of the user agent of Opera running on Windows 10.
Opera itself uses the same engine as Google Chrome so the method to change the user agent in Opera is the same as Google Chrome. To change the user agent of Opera, first click the Menu button on the top-left corner and select Developers -> Developer tools or simply press the Ctrl+Shift+I buttons on your keyboard.
As the Developer tools window opens, click the three-dot icon on the top-right corner within the window and select More tools -> Network conditions.
Scroll down your mouse to the User agent section and uncheck the Select automatically option. Select your desired user agent from the drop-down menu and reload the current page to apply the change.