Unfortunately, LibreOffice lacks a direct way to clear all direct formatting EXCEPT bold, italic, and bold-italic when using its in-built Paste Special options; normally, we end up either clearing all formatting and getting just the raw text, or we also receive font information (style and point size) with the pasted text that we do not actually desire to preserve. In other words, if we preserve bold, italic and bold-italic (or strong, emphasis and strong emphasis) character attributes when doing a Paste Special operation, we also end up receiving the font face and font size that had been specified with that text in the source document—which can be a huge problem, and that’s because as soon as we attempt to override the receive and thus pasted font information by specifying a desired paragraph style, it does NOT work: the pasted font and its pasted size are preserved and remain in-place, irrespective of whatever typeface and point size is contained in any paragraph style we try to set. So, we are ordinarily left with only two options: 1) manually override the font specification APART from the paragraph style, or 2) remove ALL formatting, including bold, italic and bold-italic during the Paste Special operation. Neither of those choices is ideal much of the time.
But, there IS a way to effectively paste our text WITHOUT the font face information WHILE preserving the bold, italic and bold-italic character attributes, a way that while a slight hassle, is far less-involved and more reliable than what others have suggested (i.e., the poor “accepted” answers to date).
Ordinarily, when we use Paste Special (V), we receive two options: “Rich text formatting (RTF)” and “Unformatted text”. If we use the first of those, RTF, then we not only preserve bold, italic and bold-italic character attributes in what is pasted, but problematically, we also preserve a) type face (font) and b) type size, when quite often we want neither of those preserved (i.e., we instead want to use the font and font size already in use where we are pasting our text).
HERE’S THE WORKAROUND:
First, go ahead and use “Rich text formatting (RTF)” with Paste Special. Yes, that will result in the type face and font size also being pasted with the text—the thing we do NOT want.
Second, select all the paragraphs of text just pasted, and use the Set Paragraph Style dropdown to select “Default Paragraph Style”.
Third, CHANGE the type face to a font NOT RECENTLY USED IN WRITER, with the Font Name drop-down.
Finally (fourth), again use the Set Paragraph Style dropdown to select the actual paragraph style you want (e.g., one you’ve created).
Once that last step has been done, you will see that your bold, italic and bold-italic formatting is preserved in the pasted text, and that your font is the one you desire (i.e., NOT the one that had originally been present in the copied and pasted text).