Examples of sources that can be primary or secondary
"A secondary source can become a primary source depending on your research question. If the person, context, or technique that produced the source is the main focus of your research, it becomes a primary source." (Streefkerk, 2023)
Documentaries
If you are researching the causes of World War II, a recent documentary about the war is a secondary source. But if you are researching the filmmaking techniques used in historical documentaries, the documentary is a primary source.
Newspaper articles
If your aim is to analyze the government’s economic policy, a newspaper article about a new policy is a secondary source. But if your aim is to analyze media coverage of economic issues, the newspaper article is a primary source.
Reference:
Streefkerk, R. (2023). Primary vs. Secondary Sources | Difference & Examples. Scribbr. https://www.scribbr.com/working-with-sources/primary-and-secondary-sources/