This question has been asked a few times on multiple fora over many years but I have yet to find a solution. Fonts with the same name and size appear much bigger on LO and OOO spreadsheets and word processors than on other apps. I am running macOS 10.14.2 and LO 6.0.7.3 on a MacBook Air but I have had this problem for years on multile versions of macOS and LO.
To prove to myself that it was real, I opened a new TextEdit doc and typed some text in Arial 10. I then typed the same text in Evernote and got a similar sized text displayed. I then got the same sized text display in Apple Pages. So they seem to be consistent.
Then I tried the same text in the same font and size in a LO text document and in a LO spreadsheet. The text size on LO text document and spreadsheet were not quite the same as each other but both were considerably larger than on the other apps - at least twice the size.
Previous answers to this question indicated that it may be related to how LO and OOO determine the screen pixel density of the device but I don’t know if that is true. It appeared to only be a problem on macOS, not Windows. Other answers were about scaling and zooming but they weren’t conclusive either. I don’t think that I’m alone with this as there were quite a few respondents with the same issue.