Template OTT > fill in next date sunday

There’s an option to add fields in templates; also date-fields with a fixed adjustment (+8 days, +3 days). I need a field which enters the date of the next sunday, between 2 and 8 days away (when you open the template on saturday, the next sunday will be shown).

In a sheet, it’s something like this

=query(A5:B;"select * where datediff(A, now()) < 14 and datediff(A, now()) > 0")

(yeah, 14 day’s …)

  1. is it possible to implent a Calc-formula or something? Which field?
  2. how can i add a date from a specific weekday, which lays between
    1 and 8 in the future?