As English is the standard language used in aviation and Zulu/UTC time is used as standard too or at least between pilots to calculate flight time and fuel. Is there any standard date format used in the industry like ISO 8601 (YYYY-MM-DD)? https://en.wikipedia.org/wiki/ISO_8601
I'm not sure if there is really an industry wide standard for the date format, but at least the ICAO (International Civil Aviation Organization) uses the YYMMDD date format for flight plans:
DOF/ The date of flight departure in a six figure format (YYMMDD, where YY equals the year, MM equals the month and DD equals the day).
Other flight plans may use different formats however. See e.g. the following example of a LIDO flight plan (Lufthansa Systems format):
(image source: SimBrief.com)
Depends a bit on where the date is used.
For flightplans, the Date Of Flight (DOF) should be inserted in item 18 in the format YYMMDD (for example 200816 for the 16th of August 2020).
In a NOTAM, a format similar to the DOF flightplan format is used, but usually with the addition of four digits to indicate the time (HHMM):
C0424/20 NOTAMN Q) EKDK/QWGLW/IV/M /AW/000/060/5601N00901E005 A) EKAB B) 2008061000 C) 2008162000 D) DAILY 1000-2000 E) INTENSIVE GLIDER FLYING WILL TAKE PLACE AROUND ARNBORG AIRFIELD EKAB PSN 560043N0090045E. F) SFC G) 6000FT AMSL
As for aeronautical publications:
4.2.3 Each AIP shall be dated. In the case of AIP issued in loose-leaf form, each page shall be dated. The date, consisting of the day, month (by name) and year, shall be the publication date or the effective date of the information.
ICAO Annex 15
This typically means 16 AUG 20, 16 AUG 2020 or 16 AUGUST 2020.