Convert From Unix Time

[timezone]::CurrentTimeZone.ToLocalTime(([datetime]'1/1/1970').AddSeconds($UnixTime))
Example
PS C:\> $UnixTime = '1553353149'
>> [timezone]::CurrentTimeZone.ToLocalTime(([datetime]'1/1/1970').AddSeconds($UnixTime))


Saturday, March 23, 2019 9:59:09 AM