So its pretty common for people to cite the crisis of the third century as being the beginning of the end for the western roman empire. That after that the cost necessary to run the empire became increasingly difficult to raise resulting in a slow downward spiral. But are we looking at it in a too deterministic manor? I mean it was a massive blow to the empire but it would take another century for Rome's actual territorial integrity to start to be chipped away.
Anyone who says the Third Century Crisis started a downward spiral the resulted in the end of the Roman Empire is, as you have guessed, definitely wrong. The Empire enjoyed a quite prosperous and strong time during the fourth century, and the disasters of the fifth century were not only far removed from the disasters of the third century, but were characteristically different.
However, the Third Century Crisis did result in a large number of significant changes to many aspects of the Roman society and the causes of the collapse of the Empire are often traced by professional historians to these factors. The Later Roman Empire, as it is often called when referencing the period after the Third Century Crisis, was more authoritarian and militaristic, with a larger and more robust, but more expensive, administration. There were more emperors and they controlled the Empire with more of an iron fist. There were also a lot of changes that were not related to the Third Century Crisis, such as stronger barbarian enemies and climate change, as well as economic and demographic changes.