Are Sentinel-2 L1C temporal images already radiometrically normalized?

I need to process Sentinel-2 L1C images of an area on different dates. I want the Time series images to be radiometrically normalized. Are they already normalized? If not, then can anyone please share how I can do this in python.

No, they are not. What you are looking for is L2A data, see ESA’s user guide for more information:

You can use L2A within Sentinel Hub: