A fresh tomato, such as one you might take off of a tomato plant, has a flavor enzyme that stops working when the temperature of the tomato gets below 50 degrees F, as might happen, for example, by putting the tomato in the refrigerator. The loss of flavor at this point is permanent, and bringing the tomato back to a temperature above 50 degrees will not restore the loss of flavor.
Canned tomatoes, including the so-called "fresh pack" tomatoes such as sold by Escalon and Stanislaus, are processed (including cooking). Once the can is opened, the tomatoes can be safely refrigerated, either as is, or as a sauce, heated or unheated. However, once opened, the typical advice is to use the canned tomatoes within a week, stored in a non-metal container. I will often prepare a pizza sauce the night before I intend to use it and refrigerate it. I think the flavors harmonize better that way. It's not really much different from the way that the flavor of a good tomato-based pasta sauce improves with a few days of refrigeration. I will also use tomatoes like the Escalon 6-in-1s right out of the can, with maybe some fresh garlic and a pizza seasoning or herbs. I'm sure you will find many other variations of the same themes.