looks like 3090 and 7090 are the last two ultra https://www.delltechnologies.com/asset/en-au/products/desktops-and-all-in-ones/technical-support/optiplex-3090-7090-ultra-spec-sheet.pdf

 the last cpu gen supported in ultra is 11th.  not able to find 12th gen or later intel cpu for ultra series.

look for third party sale of 7090 ultra such as ebay.

@redxps630​ , just wanted to know whether Ultra is still or no longer in Dell product line :) If no longer, then perhaps better to look for others.

Dell does not seem to make it any more.  It is a good model but perhaps based on saled record they decide it was not profitable enough.  so now the smallest they make is micro.  but it may come back, never know.

current Optiplex form factor line up for 13th gen