Create a new table in Power Query using the 'Enter Data' function on the Home tab. Enter into the first column all of the values you want to be repeated for each date. Let's say you call this new table 'repeatList'.
Once you have that table, you can right-click it in the query list and uncheck 'Enable Load' - it doesn't need to be sent to your data model.
In your table with the dates in, create a new custom column and, as the calculation, just enter ' = repeatList '.
You can now expand your new nested tables column to have each date repeated for each value in your repeatList query.
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