The framework of Introduction can be seen as a "funnel" from large to small, that is, the process of starting from a broader field and gradually narrowing down to your research objectives. Take my own field of biomedicine as an example. Firstly, the first paragraph can describe the background of the research and the necessity of the research. Then it points out the shortcomings or research gaps in the current field (mainly points out those related to their own topics, and simplifies them); Then introduce their own research topics, what problems can be solved or why is better than the predecessors; Finally, the core methods and main findings of the paper are summarized.