For events like Prime Day, you can use the "One-Time Bid Increase Ruleset (Tentpole Event)" bid template provided by Adbrew. To use it:
Click "+ Add New Ruleset"
Click on the "Create from Template" option
Select the "One-Time Bid Increase Ruleset (Tentpole Event)" under the "Bid" dropdown
Click on Next and Confirm
Once added, you can link your campaigns and update the date and time at which you want the ruleset to run. They will not run for a second time unless you change the date to a future date again.
After the event is over, you can undo all the changes that this ruleset made very easily to bring your account back to the normal state.
Go to the Rulesets page and open your ruleset
Then go to the Change History tab inside the single ruleset view
Increase the rows per page and select all the changes that were made
Click on the Actions button and select Undo.
All the selected changes will be reverted. If you have more than 300 changes, you may have to do this more than once, as not all the changes will get selected together.
Note: If you have made manual changes to those bids after the ruleset increased it, and then try to undo the changes, they will get reverted to the original value before the rule ran (regardless of what the manual change was).