Contents that are stored on the clipboard can be pasted into your document using different formats. In LibreOffice you can choose how to paste the contents using a dialogue or a drop-down icon.
The available options depend on the contents of the clipboard.
In Writer text documents, you can press Command+OptionCtrl+Alt+Shift+V to paste the contents of the clipboard as unformatted text.
Pasting clipboard contents using an icon menu
Click the arrow next to the Paste icon on the Standard Bar to open the menu.
Select one of the options.
If you do not like the result, click the Undo icon and then paste again with another option.
Pasting clipboard contents using a dialogue
Choose Edit - Paste special.
Select one of the options and click OK.
If you are in a spreadsheet and the contents of the clipboard are spreadsheet cells, then a different Paste Special dialogue appears. Use the Paste Special dialogue to copy cells using basic or advanced options.
Transpose: swaps the rows and the columns of the cell range to be pasted.
Link: pastes the cell range as a link. If the source file changes, the pasted cells change also.
The other options are explained in the help, when you call the Paste Special dialogue from within LibreOffice Calc.