First, a link to the online help: https://tasmota.github.io/docs/Commands/
Now, the relevant bits from that page as of Jul 14 2020:
0 = enable NTP (default)
1 = format JSON message timestamp in ISO format
2 = format JSON message timestamp in both ISO and Epoch format
3 = format JSON message timestamp in Epoch format
<value> = disable NTP and set UTC time as epoch value if greater than 1451602800 (January 1, 2016)
Set policies for the beginning of daylight saving time (DST) and return back to standard time (STD)
0 = reset parameters to firmware defaults
H,W,M,D,h,T = combine the below items into one command
H = hemisphere (0 = northern hemisphere / 1 = southern hemisphere)
W = week (0 = last week of month, 1..4 = first .. fourth)
M = month (1..12)
D = day of week (1..7 1 = sunday 7 = saturday)
h = hour (0..23)
T = timezone (-780..780) (offset from UTC in MINUTES - 780min / 60min=13hrs)
Example: TIMEDST 1,1,10,1,2,660
_If timezone is NOT 99, DST is not used (even if displayed) see
Timezone -13..+13 = set timezone offset from UTC in hours
-13:00..+13:00 = set timezone offset from UTC in hours and minutes
99 = use timezone configured with TimeDST and TimeSTD
Check the current time with Status 7
These are the commands to enter to setup time for North America Eastern Time Zone w/ DST enabled
TimeSTD 0, 1, 11, 1, 2, -300
TIMEDST 0, 2, 3, 1, 2, -240
TimeZone 99
Status 7