The toolbars Icons are very small and straining to eyes

Technical Problems SketchUp
12

You can increase the size of UI elements via Windows Settings.

Start > Settings > System > Display

Choose the display that you run SketchUp on, then scroll down to Scale and layout,
and set the display scaling to a higher percentage. The control is labeled:

Change the size of text, apps and other items

NOTE: SketchUp supports up to 150% display scaling.