I think this is kind of up to you to be honest.
There are a lot of things you can do such as go on service trips abroad, engage in research, if you have any unique abilities or hobbies mention it, work experience, etc
Overall, I think you should try to do something unique for yourself.
I know a lot of people do the standard things like service trips abroad and volunteering at hospitals, which is fine.
Although, I didn't do either of those two and my experiences were mostly my unique work experiences, and pursuing hobbies that I genuinely liked. I feel that adcoms liked this about me and in my interviews several interviewers told me that my application/ extracurriculars seemed "real". By that,meaning that I wasn't doing a lot of the standard ones that many predents do solely for the purpose of making their application look good.
It also stimulated good conversation and helped the interviews go smooth.
Let me know if I can be of further help!
Good Luck!