Select the rows where you want new lines inserted
Right-click the selected rows
Click Insert
To insert multiple blank rows at once, select the same number of existing rows as the number of rows you want to add
Use the keyboard shortcut Ctrl + Shift + + after selecting the rows
To insert multiple line breaks within a single cell, press Alt + Enter while typing in the cell
On Mac, use Control + Option + Return for a line break within a cell
To insert rows using the Home tab, go to Home > Insert > Insert Sheet Rows
To insert multiple rows quickly, copy a range of blank rows and paste them where needed