Conditional Format from current time

I have programmed a cell "b" that when I enter the current time into cell "a", it calculates a time 2 hours after the time entered into "a". Is there a way that when "b" is 30 minutes from the current time on the computer, or when the time in "b" is the same time at the computer, that the time can turn bold or fill with a color (like with conditional formatting)? Kind of a "live" document associated with the computer's time.

Or, can I enter a "clock" into a document and then apply a condition based on that inserted clock?

THANK YOU for any thoughts and recommendations!

How often are you changing the contents in cell B? Are you updating B throughout the day?