I need script to cycle RGB light each time it runs (16 Colors )

Configuration
1 
type or paste code here
2

Perhaps ask in the configuration section for help and show what you’ve tried. This section is typically for complete working implementations.

3

Indeed not the correct forum section, maybe a mod can move this post?

I use the following automation. For me it cycles through a pre-defined list of colours (as set as a helper) every 10 minutes. In your case you could change the trigger to your light switching on

alias: RGB buiten loop
description: ''
trigger:
  - platform: time_pattern
    minutes: /10
condition:
  - condition: state
    entity_id: light.buiten_tuin_spots
    state: 'on'
action:
  - service: light.turn_on
    target:
      entity_id: light.buiten_tuin_spots
    data:
      color_name: '{{ states(''input_select.light_colour'') }}'
      transition: 30
  - service: input_select.select_next
    target:
      entity_id: input_select.light_colour
mode: single

For the rgb colours:

input_select:
  rgbkleur:
    name: "rgbkleur"    
    options:
      - aquamarine
      - blue
      - blueviolet
      - cadetblue
      - chartreuse
      - coral
      - orange
      - darkorange
      - tomato
      - orangered
      - red
      - crimson