Matters of aesthetic spacing should be handled with paragraph padding, rather than inserting empty paragraphs into the document. Try this:
- Put your cursor into the block qoute.
- Use the
Format ▸ Paragraph ▸ Line and Paragraph Spacing...menu command.
As you adjust the before & after paragraph spacing values, toward the bottom of the dialogue, you will be able to preview the result in the main editor. Once you get a look that you like, confirm your settings, and then update your Style. All of your block quotes should update to the new look.
There is one caveat to this, and that is that unlike more complex style systems, such as those found in word processors, it does not have a concept of contiguous formatting vs “endcap” formatting. You can’t say, add space to the beginning of a sequence of block quote paragraphs, but not in between each block quote paragraph, if that makes sense.
Consequently, you may find it best to save this layout tweak for after you compile. With the text fully styled, it would be a simple matter to implement the padding in a way that works well with multi-paragraph quotes, in Word or LibreOffice.
Of course, if you only have single-paragraph quotes, you can skip that.
And I suppose another approach could be having two additional styles: “Block Quote - Start” and “Block Quote - End”, with the use of regular “Block Quote” for middle paragraphs. The “Start” style would pad before the paragraph and the “End” style would pad after. Honestly some people use that approach in regular word processors as well.