It is suggested that the discipline should consider the cross direction between statistics and other disciplines, such as biostatistics, system reliability, economic statistics and so on. Of course, this needs to be combined with resources around the subject, such as your own tutor. Although he is doing operational optimization, you can consider using statistical knowledge to solve problems in this field. As far as I know, operational optimization needs data modeling, assumptions about the system, estimation of data distribution and so on. The subject can do some "parameter estimation" work in this respect, and then combine with the specific research field, and then publish the paper to the journals in this field, rather than purely statistical journals.
What I want to say next is how to find good ideas and how to write a good paper, which is not only useful for statistics, but also applicable to other majors. First of all, learn more about some journals in this field, both good and bad, and see what types of articles these journals tend to receive; Then, read more papers, grasp the research hotspots, summarize more, and find your own ideas; Finally, determine a feasible and innovative idea with moderate difficulty to write the thesis.
Don't ask too much about the subject. As long as it is SCI, you can learn more about the periodicals in SCI four districts, and it is relatively easy to publish papers. In the whole process of academic paper creation, don't forget to communicate with your tutor. Although he is in the field of logistics, you can learn from his valuable experience in writing and distributing papers and avoid detours!