Is work experience as a foreign service officer relevant for public health, epi programs?

[Desperado7261]

Hi, I'm a potential international applicant for PhD programs (maybe fall 2024).

Currently working as a foreign service officer, I expect my career to be 5-year experience, including a couple of years in a developing country in South-east Asia possibly.

My major was sociology (undergraduate) and was quite much interested in public health (or more specifically, demography, health disparities, social epidemiology) but I finally started my job for mainly two reasons: a) i wanted to know whether I prefer real-world work to research and b) i needed some financial surplus. 

Nevertheless, my goal is to quit the job within a few years and get into PhD program in my interests. Im currently a graduate student for statistics in an open university in my country.(its not so much demanding as top-notch schools though)

My question are as below:

Im still quite not very convinced of the exact field I'd like to study (and its the biggest problem, I know).

Do you think a diplomat career would help getting into PhD program? If so, which program do you think will be most appropriate for me? 

My undergraduate thesis was about the quality of employment of workers in their 50s-60s and its effect on their self-reported health status.(not very sociological, but social epi. I think)

My interests started from that topic but Im also interested in health systems and policy evaluation, too.

You can see me perplexed, I agree but as a forerunner, which advice could you give for me?

Thousands of thanks in advance.