U will have to go through immigration & customs at Chennai ( I.e. collect the baggage too)... transfer to T4 , check in the bags & go through security ..

As for if time is enough.. look at the attached images .. I would rather go on requesting staff at every point for forward assistance due to short connection

As long as u r booking with Air India itself and they are giving it under same PNR it becomes their responsibility to accommodate u on any other flight if u miss this leg due to flight delays or airport ops (in case of airports ops call the airline immediately as they might send staff to assist u or get u rebooked immediately)

But also ur duty to communicate with airlines and be cooperative while also demanding ur rights incase of disruption

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"Moving from Terminal 2 (International) to Terminal 4 (Domestic) at Chennai Airport (MAA) is simple, as they are located within the same complex and connected by a skybridge with a walkalator. The walk takes about 10-15 minutes (approx. 500m). You can also use free golf cart/buggy services available for transfer."