Hello and welcome to the forums.
A well maintained volvo will probably outlive the human race in all fairness. If the history is good and everything works and runs sweet then it should be okay.
The gearbox is a good unit too, but despite what volvo say, they do need oil changes and more regularly as the mileage increases. Some people incorporate a gearbox oil change into their yearly servicing to keep things running smoothly. Don't be put off by this as it's really simple to do yourself and fairly inexpensive also.
There's tons of guides and help available on these forums should you have any issues, we are a friendly bunch 😉
Also take a look at this chart of high mileage Volvo's. Its pretty impressive:
https://www.volvoclub.org.uk/hmc/