Hello @faustocapellanj
Thank you for taking the time to reach out with an answer. I really appreciate you doing so.
As always John Liu article is excellent.
My biggest problem is 'how to get the sample payload to paste into the schema.'
Example Flow structure.
A Power App trigger, initialise variable, Parse JSON.
Try to save the Flow to run and you cannot save so cannot run generate the sample schema. If there is no parse Json trigger how is the schema generated i.e. where is the scheme to copy and paste.
I included an image of a succussful Flow but this is after much trial and tribulation (created the scheme myself). There simply must be knowlege missing in my understanding.

Ideally a step by step illustrative guide would be helpful i.e. removes any ambugities and makes no assumptions as to user understanding. Searching the internet I know I'm not the only one frustrated with the quote 'run the Flow to generate JSON scheme.'
Thank you and have fabulous day.