While Optimize is on, it manages your campaigns, so edits made in Google Ads are replaced on its next run.
The one exception is pausing: pause a campaign in Google Ads and Optimize keeps it paused and shows it on your dashboard. A campaign Optimize paused is paused again if it's turned back on.
If you raise a budget in Google Ads and your budgets then add up to more than your daily spend, your dashboard says so and offers to raise the daily spend to match. Optimize leaves the new budget for one run so you can choose, then brings budgets back within your daily spend.
Stop Optimize from Settings at any time to manage everything yourself.
See it on your own accounts
Free plan, no card: see everything Optimize would change before you pay.