As above said, something like the shroud is a great template for a raid. The best raids have all this in multiple distinct phases -
1) DPS phase/elements
2) A puzzle phase/elements - something that the whole group can engage in. A small puzzle for each person (ex. shroud, too hot to handle, RTSO) is far better design than 1 single puzzle that realistically only 1-2 people can do while everyone else stands around with nothing meaningful to do (ex. Deathwyrm, Reaver's Fate, Titan)
3) Group coordination phase/elements - Can be many things but something that requires the group to communicate, organize and work together in some meaningful way that can't just be solved by DPS (ex: Strahd card phase, shroud phase 2, PN laser/unsolving puzzles)
4) Boss fight
Every raid doesn't have to have #2 and #3 necessarily, but if it's a full priced expansion that only has 1 raid it should have all 4 of these things. But if an expansion has 2 raids for example, one can be a DPS focused raid and the other can be a more coordination/puzzle focused. If adventure pack or f2p raid, less elements/smaller scope is fine and understandable.
My main concern is there's a trend in newer recent raid releases where the scope is being cut back as compared to older raids, and the raids tend to only have 1, maybe 2 of these 4 things and as a result be too small in scope. More raids like Skeletons, Strahd and Shroud in expansions and less raids like Relentless unless it's going to supplemented by a 2nd raid in that same expansion, in which case a small scope simple raid may be fine.
Edit: Oh yeah I forgot map design/story, that's really important too. The raid should IMO be the climax and resolution of that expansion/adventure pack's storyline. The map/setting should be atleast somewhat distinct. So preferably some unique art assets and/or some kind of creativity or complexity into the map design that goes beyond a normal quest. It shouldn't just be generic rooms/hallways...looking at you Threats Old and New, and I think each raid should have it's own unique music track to give it that epic and special feel.