How to get data from server directly to a input box of a form?

Yes, if I understand your question correctly, it’s very easy.

Further to the link Ben provided, these high level steps below might help along those work instructions:

  1. Create a database query in Server Connect that returns the data you want to display inside your input elements.
  2. Add a Server Connect component in App Connect and select the action you create in step 1.
  3. Go to the properties panel of your input elements and select Dynamic Attribute. Choose Inner Text
  4. Click the lightning bolt and choose the fields/values you want to display in the input field.

This is how I do it. In most cases though you would want that server connect query to be returning just one row of data, so it usually would be filtered by a record ID.

If you’re wanting to display that data of many records you’ll need to work with Repeats or repeating tables.