Way to show tasks for an actual week from Monday to Sunday

I would like to see that too! As it stands I think your best option is a plugin.

(We basically don’t know what day of the week today is)

Alternatively an unreliable query I build for myself.

#+BEGIN_QUERY
{:title [:b "Next Sunday"]
 :query [:find (pull ?p [*])
  :in $ ?day ?today
  :where
   [(- ?today ?day) ?diff]
   [(mod ?diff 7) ?n]
   [(- ?today ?n) ?sunday]
   [?p :block/journal-day ?sunday]
 ]
 :inputs [20230604 :today]
}
#+END_QUERY

What it does is it determines what the following Sunday is from today based on an input date that is a Sunday.
Because this is all integer (numbers) work though, it can give odd/no results when going to the next month. It will determine the next Sunday is 20230598 (recent example).
Which returns nothing.
It’s a hack basically.

Check out this feature request as well: