Hi again
As far as I know, Power Automate does not have a broad set of date format manipulation funtions as other environments (I am thinking on moment.js for example).
If so, this means you have to use expressions to adapt it to the format required by the destination, it your case Sharepoint. IN this post you will find different approaches to solve a similar problem.
If I were you, I would suggest to implement a test flow (manually executed) and verify which is the format more similar to the one you got that is accepted by Sharepoint connector (i .e. when we request to add a new item from PowerAutomate) as proper date.
Please note this is the standard format used by PowerAutomate:
2018-04-15T13:00:00.0000000Z
I believe there are several formats currently accepted by Sharepoint connector, but let's assume this is the only format accepted by Sharepoint connector, this means:
-you need to split 1/27/2020 in three pieces by using '/' as the separator, and build the required format by changing its order.
So if you apply the following expression...
concat(split('1/27/2020','/')[2],'-',split('1/27/2020','/')[0],'-',split('1/27/2020','/')[1],'T00:00:00.0000000Z')
...you will get:
2020-1-27T00:00:00.0000000Z
-if Sharepoint accepts this format (2020-1-27T00:00:00.0000000Z) then you got it! If not, probably you will need to declare the months and days with two digits, also by using expressions. So, you can evaluate the length of
split('1/27/2020','/')[0]
If length is 1 you should concat a 0 at the beginning of the month.
Hope this helps