Assuming you're using Opus 12, you most likely have Windows configured with DPI compatibility settings on for Opus. They should all be turned off, which will allow Opus to scale the fonts and icons appropriately.
(You may need to reset some of your font sizes in Preferences after doing this, if they were set larger than normal to compensate for this.)
See Windows Compatibility Settings / Wrong DPI / Installer misdetects OS for how to check the compatibility/dpi settings.