Requirements: At least an iPhone or iPad with iOS 16 and an A12 chip.
To create a sticker of a person or object, open the appropriate image in the DC-Gallery.
Then hold your finger on the relevant part of the picture and wait a moment.
The object/person will now automatically be recognized and marked.
After that, you can copy it to the clipboard and paste it into any chat.
DC-iOS will interpret the clipboard content as a sticker and then send it.
To store the sticker, send it to yourself (Saved Messages).
Now you can save it in DC-Desktop: right mouse button → “Save Sticker”.
Tagging objects in photos is also possible in the iOS Photos app, but I find it very convenient that it works directly in DC too.
Other messengers like Threema, Telegram and WhatsApp cannot do this in their gallery.