If you mean it's tiny only in your browser, then as ukbod2015 says, use the browser zoom controls.
On the other hand, if you find it too small everywhere, the chances are you had the display set to the wrong resolution previously in order to make it bigger, and W10 has corrected it for your monitor. This would probably be caused by erroneous advice of often seen posted on here.
Right-click on a clear area of the desktop, choose Display Settings, and use the slider bar to make stuff bigger. This does it the correct way, by scaling the DPI setting, rather than changing the resolution.