Board Thread:Support Requests - Getting Technical/@comment-251688-20201022173806/@comment-9605025-20201022190042

Well, if you feel like it, you could ask staff about Category Intersection. Since your wiki already had it, they might consider fixing it for UCP for you. However, they also might not since it appears to be a non-standard extension. You won't know unless you ask.

SMW needs to be "implemented" only if you plan on using its page properties feature (and again, Fandom is not enabling it on wikis that don't have it). If you are just using categories and/or template parameters, DPL is good enough. I think you have to request DPL. You can check by going to Special:Version. If the DPL tag isn't listed there, then it isn't enabled yet.