Start with the simple stuff - fan belt tensioned properly? Is this the original radiator? If so, good chance that it is getting pretty clogged - particularly if you have not flushed the coolant system every two years since new. How about the radiator fins - have you cleaned them out from the rear with compressed air to blow all the bugs and crud out? Be sure that your radiator cap is holding the proper amount of pressure (have it tested, or simply get a new one - they are not that expensive and have a history of failure).

Deeper in - how old is the water pump? I have seen old ones - particularly some of the cheaper aftermarket pumps with eroded pump vanes inside to the point that the pump is not moving any water through the system. Difficult to know if this is a problem without removing the pump - and at that point, you might as well replace it having gone through all the effort to get the old one off.

Have you tried turning on the heater to full and the fan on high - if this brings down the temp, then you likely have a clogged radiator - either outside or inside. If it is original and clogged, you will be better off to replace it with a top quality aftermarket HD 3-row like a Nissens as opposed to a new Volvo one. Trying to clean out your existing one is likely not a viable option as they get a bit thin over the years.