This will change the overall desktop resolution. Don't use this if you switch between fullscreen and windowed mode frequently. The desktop will change back to normal after you close the game.

1. Download Res-o-matic: https://www.bcheck.net/apps/reso . Place it anywhere you want (I put it inside the installation folder for convenience).
2. Right click the program then select "Copy as path".
3. Open the game properties. In the launch options paste the program path then type: %command% <your desired width> <your desired height> 32 <your screen refresh rate> (example: If I want to run the game in 1280x720 at 60hz then the launch options are -> "D:\SteamLibrary\steamapps\common\Wuthering Waves\reso7.exe" %command% 1280 720 32 60)
4. You should get the game run whatever the resolution you want.