Apple - Can I modify the "move" calories for a pasta day?

You could change the date of your iPhone/Apple Watch to that day and then burn 2 calories with an activity of your choosing. After this change the date back.

Another option is to record a new activity on the Health app. Go to the app, choose Activity and then choose "Active Energy", then press the Plus sign and insert the Date and the burned calories.

No. You can change the move goal for the current day or tomorrow, but not for the past without jailbreaking or decrypting the data store.

The pragmatic way is to set a daily alarm - 10 pm or another such time when you "Do or Die" and close all the rings you need since trying to "fake out the move goal" by lowering it late in the day doesn't seem to work when I've had people try it. I just miss my goal after trying once with the original watch to dial back the goal one day I didn’t think I could make it.

For completionists - ensure you surpass what you had planned at midnight when the day started and make sure you exceed any increase you might choose during that day.