You can copy text from a file with Alt+I,L, but you may get formatting you don't wish to have. There are a number of variables, depending on the two documents.

I recommend, instead, selecting and copying the desired text from the other file, then using Paste Special by pressing Ctrl+Shift+V and selecting Unformatted text from the list of options. This will make the imported text conform to the paragraph style of the new document, wherever the cursor is. So, for instance, if you cursor is starting a paragraph that is Calibri 11 pt, with single line-spacing, that's what you'll get.

Does this solve your problem?