I have not seen any wiki have completely different site design for a subset of pages. Nor do I see Arrowverse wiki doing something special for Lucifer pages but not their other series.
Regardless, there is no merge. No admins from Arrowverse have requested a merge and, at this time, Lucifer Wiki would reject it. Lucifer Wiki would only agree to a merge if a) the actual Lucifer TV series is shown to tie in with Arrowverse [more than one irrelevant - to Lucifer series - scene in a different show] and b) a merge would benefit the Lucifer Wiki & Lucifer fans. At this time, neither condition is met.