To be able to change Timezone on Alpine, we first need to make sure alpine-conf package is added, as by default Alpine Base Image doesn't come with unnecessary packages to keep Image size as low as possible.
Example
$apkadd--updatealpine-conftzdata
This will add necessary setup scripts on Alpine. And to actually change Timezone, we can run following command -
$setup-timezone-zIST
This sets the Timezone to IST, and we can now remove setup scripts package if required by optionally running -