Hi,
There is not any such variable type that can be used for the dates in power automate, it can be stored in string type. Instead of this I used Compose action and just stored the date in value.
Using this original format type is reserved and does not need any conversions ahead.
To further work with updates such as adding, subtracting, etc. we can directly save these actions in compose variable or if already saved, 'Outputs' from compose action can be used.