There are many ways to develop a research topic. Here is one technique:
*You may not find anything and that's okay
Sometimes, no one has written about your specific research focus. In that case, you will need to break it up into a few different searches and synthesize/combine the information.
For example, if you search birthmark Hawthorne postcolonial in Library Search, there are no results. But there are results if you search birthmark Hawthorne and do a separate search for postcolonial literary theory.
After seeing some directions that your topic can take, you need to find your research focus. Visualize your topic as branching arrows with the different subsections of your topic flowing out from your topic. Your research focus can be one of these arrows (aspect) or a grouping of arrows (theme).
Some topics can be broken down into many individual parts and while they are all related, one part stands out to you. It can be discussed on its own and has enough resources available for your project. This can be a specific instance of your broad topic. For example, if your topic is LGBTQIA2S+ representation in media, an aspect would be a specific character.
Other topics have individual parts that are best discussed in small groups. There's an overarching theme that ties them all together. While this is more specific than the broad topic, it still has a few separate ideas. The theme approach is best used when each individual aspect of a topic does not have enough information on its own. For example, if your topic is social media influencers, a theme would be authenticity which can be broken down into self-branding, ethics, and self-image.
These books provide overviews of specific theories and/or literary criticism. They may help you develop your research focus.
An argument or thesis statement is best developed closer to when you begin to write your paper or create your project. At that point, you have found most of the available information on your topic and can form a solid, unchanging opinion or idea around it.
A research focus helps guide your research just as a thesis statement guides your writing but a research focus changes and evolves as you encounter new information.