I cleaned out a MBP of similar age while replacing the battery. There was quite a bit of dust trapped in the CPU fan, as well dried out thermal paste. Between new battery + cleaned fan + new paste it runs 'like new'.
(Unfortunately the dGPU on the machine appears to have developed a fault which might put it into retirement for good)
(Unfortunately the dGPU on the machine appears to have developed a fault which might put it into retirement for good)