It's best to take a look at an introductory textbook on tax theory and tax policy. There you will also find approaches to specifically address your question scientifically.
To check for recent authors, research gaps, variables, findings, etc. about the effects of high taxation, you may want to do the following:
1. Choose a number of peer-reviewed research papers related to your high taxation, from Google Scholar, RG, SSRN or similar credible websites, not from non-credible sources.
2. Read these research papers and check for the research gaps from within such research. You may find these gaps under the subtitle: Future Research or similar subtitles.
3. Ensure that such gaps are not already covered by recent research. That is, for the gap that you want to cover, read to the last current research in this regard to make sure that no other author(s) already conducted such research.
4. Then, go ahead and start preparing for your research, preferably using the Literature Review Matrix where you put a table showing authors, title, objectives, research question(s), problem statement, variables, methodologies used, findings, etc. for each research paper selected. By the way, you may want to keep such relevant research papers to use them as references in your research.
Determine the effects on a micro and macro levels that include individual behavioral characteristics, disposable income on homesteads, overall economic growth.
Engage policy makers who determine tax thresholds
Utilize available research products for your reviews