How to change a unix datetime into a different timezone unix datetime

I get datetime state like: "2022-05-18T18:30:00.000Z" - a moment datetime, then converts it to unix. But I do convert it in my local timezone, How do I change the timezone of the unix datetime and return in same unix format.

Timezone I get - Asia/Singapore

Code:

this.state.startTimeDate.unix() //This is how I convert it to unix format

How to change this unix to a different timezone ?

Copyright Notice：Content Author:「Sai Krishnadas」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/72301960/how-to-change-a-unix-datetime-into-a-different-timezone-unix-datetime