Do you want something like
getZoneOffset() {
#assume ./zones.txt contains lines like
#example.com 3600
#i.e. host and time offset in seconds
remote=$1
set - $(grep "$1" ./zones.txt)
echo $2
}
zoneOffsetSecs=$(getZoneOffset $remote)
now=$(date -u +%s)
there=$((now+zoneOffsetSecs))
date -d @$there
You may want to add error handling for cases where your remote host is not found in your zones.txt file.