fieldcompose

This module provides a new Field Type which allows defining multiple fields in field settings with YAML based syntax and by respecting exactly the structure of Form and render elements

A good use-case for when to use it is if you have a component with multiple configuration options, e.g: a slider library in which case you can avoid having 10+ addition tables(+revision tables) if you would implement normal fields for this purpose by storing values as JSON.

With this approach, you might a expect slight increase in CPU usage as field values are decoded from JSON but this exactly what you might want as lots of time CPU is underused and DB operations are expensive(especially in a cloud env)

Example configuration bellow

-
  id: my_bool
  _type: checkbox
  _title: Enable something
-
  id: my_string_field
  _type: textfield
  _title: Enter something(State dependent field)
  _required: FALSE
  _states:
    visible:
      ':input[name="$field_name$[$field_item_delta$][my_bool]"]': { checked: true }

will produce

Disclaimer

This module is for simple, multi-fields and is not meant to be a full-on replacement for using entity references, Media or Image fields.