I journal every day into the same google doc and I start each entry by typing the date and weekday each morning. Because I do this so frequently, I decided to look for a solution to automate inserting this text into my journal entry.

I found this example app script that got me most of the way there. The only thing missing was the format of the date that I use.

Example of the date format I use: 2021-04-07 Wednesday

additional date format settings are documented here

The app script code in this repo is largely borrowed from the stackexchange answer and modified slightly to output my preferred date format.