I wish they would publish that array set of functions to 2019, it would feel very frustrating to have a version already so outpaced by content available only to 365.
Yes, you may find that in comments from Microsoft here https://techcommunity.microsoft.com/t5/Excel-Blog/Preview-of-Dynamic-Arrays-in-Excel/ba-p/252944
Dynamic arrays will not be in Excel 2019. Excel 2019 has just been released and this feature is only just making it into O365 insiders.
Maybe in some future. Maybe not.