I have a form that included three sections, I want three tables for each sections when submit click. I used repeat but it create instances instead of creating a single table. And I want to make a relationship among those three tables as well. How can I achieve this using survey123 desktop.
Yes, this should be possible using repeats/related tables. If you create a parent layer (main layer) that has some questions, and then create 3 repeats (related tables) to that parent layer, they will all be related to the parent record that gets created, and you will have 3 tables in your feature service related to the parent layer. Is that what you want to do?
If you just want the 3 tables and not the parent layer, you can create the schema as above, and then create a new survey based on existing feature service, and remove the parent layer fields, and just have the 3 tables as repeats in the survey form.