There are lots of possible approaches that could be used to base a research paper on the comics. The first step would be to be certain you are aware of any requirements or restrictions that might impact your assignment.
You could choose one specific comic strip and examine how changes in society have been reflected through changes seen in the strip. Any comic that shows characters aging over the years that the strip has existed would easily support this purpose, reflecting different activities by the characters, different expectations, changes in clothing styles, and so on.
Using a variety of comic strips could allow you to analyze how a common theme is portrayed in a variety of ways. Consider the many types of family dynamics that are found in a selection of today's comic strips, for example.
You could focus on one comic and consider a recurrent theme in that strip and how it has been developed over the years. If a comic makes reference to a concern such as economic conditions, the need to care for the environment, or some other social topic, how has the passage of time impacted the message and/or the way in which it is presented?