Enter the first two cells of the pattern
Select both cells
Drag the fill handle down or across
Double-click the fill handle to auto-fill adjacent rows
Use the Fill series option from the fill menu if available
Copy and paste the pattern range into the target cells
Use formulas with relative references to continue calculated patterns
For custom lists, create the list in a column and drag to extend it
For dates, enter two dates or one date plus the next increment
For numbers, enter the starting values that define the sequence
For text patterns, include consistent prefixes, suffixes, or increments
Use the Explore or autofill suggestions if Google Sheets offers them