How to properly describe future works in Master's Thesis?
Science is never complete. If the work that you have done in your master's thesis has been worthwhile, the most likely outcome will be that other researchers will want to develop your work further. Since this is the standard state of affairs, there is a standard place for describing future work in your thesis. This place is at the end of the Conclusions chapter. If you are writing that chapter well, you can both address future work that remains to be done, and give the impression that the work in your thesis has been worthwhile.
Your Conclusions chapter will start off by recapping what you did in your thesis; a short, high-level summary. Then, you will refer back to the problem statement and substatements you posed in your Introduction chapter (or maybe you put them in a separate chapter; this is also fine). For each problem statement and substatement, you will now methodically describe how the statement has been answered in your thesis, with explicit references to specific evidence in tables, figures, or the text. Once you have described how the problem statements have been answered, you then turn to describing future work, perhaps in a separately numbered subsection of the Conclusions chapter.
By building up your Conclusions chapter like that, you can give proper space and attention to work that remains to be done, while also giving a clear overview of the contributions of your thesis itself. If you refer back to the problem statements at the start of your thesis, you make a very structured impression: the start of the thesis and the end of the thesis are connected, and you summarize what you have done. So you combine sounding unbiased with discussing future work while also keeping the focus on what your research achieved.