Here's how you can replace all line breaks with paragraph breaks using the Find and Replace feature in Word:
Open your Word document.
Press Ctrl + H on your keyboard to open the Find and Replace dialog box.
In the "Find what" field, type ^l. This is the code for a manual line break in Word.
In the "Replace with" field, type ^p. This is the code for a paragraph break in Word.
Click on "Replace All". Word will search for all manual line breaks and replace them with paragraph breaks.
Once Word has finished replacing all the line breaks, you can close the Find and Replace dialog box.
That's it! All manual line breaks should now be replaced with paragraph breaks in your Word document. Make sure to review your document to ensure that the formatting is as you want it.