Can You Calculate Future Dates Based On a Start Date?

Is there a formula to calculate dates? For example, if you enter a start date, can you then calculate out what date it is 3 days after the start date, 10 days, 20 days?
Setting up a tracking system for honeybee queen rearing. Different actions need to be taken on different days after the eggs first appear. Hoping to autofill with dates instead of counting days from the start date.
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Khona