Just wanted to let people know, in case you need opera to be set at 100% while windows is set at other scale. (I wanted to add this to an old post but not possible, so here I am)
The launcher flag for me until earlier today used to be:
but now it changed to be like Chrome:
So I'm just using both for now (in case Opera goes back to the old one), like this:
"C:\Program Files\Opera\launcher.exe" --alt-high-dpi-setting=96 /high-dpi-support=1 /force-device-scale-factor=1
Remember you might need to relog or restart windows so this works correctly.