Canoscan 4.9 and Catalina 10.15.7. Is there any way or any upgrade available to enable Canoscan 4.9 to work with the Catalina 64 bit software??

Canoscan 4.9 does not work with Catalina. However you can scan using from Image Capture or from the Printer/Scanner System Preferences.

Had you mentioned your specific Canon scanner model, and if you were having issues using Apple's Image Capture, then I could have checked to see if the scanner was supported by the 64-bit VueScan Professional, and whether it required vendor scanner drivers, or none at all to perform scanning on the device.