delete multiple carriage returns

Use "Find & Replace." Go to Edit > Find > Find or type ⌘F to bring up the Find box. Then click on the gear down arrow to choose Find & Replace. Then, in the first box type \n\n (\n is the code for a paragraph return). In the second box type \n then click Replace All.

Good afternoon Jammie of Christchurch,

Welcome to the Apple Support Communities!

I understand you imported a Pages document to your Mac. To delete multiple carriage returns, select the blank lines and press the Delete button. Or, place your cursor in front of the text that you do want (for example, the "O" at the beginning of this sentence), and then press the backspace key to delete the blank spaces in front of it.

Select text and place the insertion point in Pages on Mac - Pages User Guide for Mac

Take care.