Control Panel when opened in Explorer is part of Windows, not a part of Classic Shell.
Click the blue "Small icons" link and change it to "Large icons". If that is still too small, you probably have a very high resolution, high DPI display. You must calculate the optimal pixels per inch (PPI) for your monitor size and resolution.
Go to this page:
https://www.sven.de/dpi/ and enter your display's resolution and size. It will show you the actual PPI of your display.
Then open Windows Display Control Panel and click the option to set a custom size and specify the DPI there. Then log out of your Windows account and log in again. The Control Panel icons should be bigger now.