You could do it with a Script or Calculation field if you’re adding the field to the inverse relationship of a one-to-many Link to Form field.
In other words, a child can get access to its parent fields as long as the parent has a One to Many relationship to the child. Otherwise you’re always dealing with an array of linked records, which implies you can’t just get one value from the relationship. Using a Script field you could ask a child or parent record for a specifically linked record’s field value. That is, if a child has multiple parent records or a parent has multiple child records, you could ask for a specific row and field get the value from.