Hallo Yogesh,

please don't feel offended, but this question makes no sense, at all, when you do not tell us what your application is.

What do you mean with real world? Isn't mcu also part or real world?

An example: If a certain signal is allowed to be touched by someone, there should be some protection circuit against ESD. This protection circuit can consist of only a 10nF capacitor from signal to ground, but can also consist of transzorb diode, or some resistor diode circuit to channel overvoltage to supply voltage. In this case using only some buffer at input or output of mcu would not make any sense, because there is no protection against ESD either.
So, it highly depends on your needs. Please tell us more about your actual application. Then we can give much better help.

The more concret your question is, the more concret will be our help!

Bye,
Kai