From what is practically used - you have things like CoDeSys where you can program PLC or Matlab Simulink which is heavily used in science and in automotive development or infamous LabView spaghetti the moment when program will get just a little bit more complex.

All are using blocks with input and output which are either having predefined function or you can define the block function with a code. Reading these programming schematics is sometimes great to understand the high level of how program is working with input data (left) towards output (right). However the moment you will introduce loops, visual programming will just fall apart like a glass hit by a hammer.