The following table contains the alphabets which can use in your custom date format inside the double quotes and what would they look like when the Snippet is inserted. The output is based on the time June 15th, 2022 2:45 PM UTC.
Year, no padding
Year, two digits (padding with a zero if necessary)
Year, minimum of four digits (padding with zeros if necessary)
The quarter of the year. Use QQ if you want zero padding.
Quarter including "Q”
Quarter spelled out
The numeric month of the year. A single M will use '6' for June.
The numeric month of the year. A double M will use '06' for June.
The shorthand name of the month
Full name of the month
Narrow name of the month
The day of the month. A single d will use 1 for June 1st.
The day of the month. A double d will use 01 for June 1st.
(numeric) The day of week in month.
The abbreviation for the day of the week
The wide name of the day of the week
The narrow day of week
The short day of week
The 12-hour hour.
The 12-hour hour padding with a zero if there is only 1 digit
The 24-hour hour.
The 24-hour hour padding with a zero if there is only 1 digit.
AM / PM for 12-hour time formats
The minute, with no padding for zeroes.
The minute with zero padding.
The seconds, with no padding for zeroes.
The seconds with zero padding.
The 3 letter name of the time zone. Falls back to GMT-08:00 (hour offset) if the name is not known.
Indian Standard Time
The expanded time zone name, falls back to GMT-08:00 (hour offset) if name is not known.
Time zone with abbreviation and offset
RFC 822 GMT format. Can also match a literal Z for Zulu (UTC) time.
ISO 8601 time zone format
You can read more about date format patterns here: https://www.unicode.org/reports/tr35/tr35-31/tr35-dates.html#Date_Format_Patterns