Hi there,
Thanks for reaching out. Please check Windows scaling options under Settings > System > Display. I am also attaching a screenshot for the reference.
If it does not help, try resetting the Illustrator preferences once. Follow instructions on help article https://helpx.adobe.com/illustrator/using/setting-preferences.html#setting_illustrator_preferences
**Please note that resetting preferences will remove all the custom settings and Illustrator will launch with default settings. You can also take a backup of the folders in case you want to. Location is mentioned in the article.
Hope it helps.
Regards,
Ashutosh