Dismissal from Technical Area

I have had a discussion with someone who advised me the law had changed with regards to dismissals of managers/coaches from the technical area. He said the correct procedure is now to show a red card and send them away. I know yellow/red cards for managers are introduced in the EFL but not the premier league. I also cannot find reference to this in the LOTG.

Any advice on what the correct procedure is? Does a red card have to be shown to the manager?
This is a trial in the EFL and possibly some other leagues. We are as you were with a quiet "off you pop" chat :)
This is what I thought! I doubted myself because it was an observer advising me. It was just an off the cuff question. No particular incident just asking what I would do in a certain situation which led to him saying managers should see the red card now.
Pretty sure this was already discussed back when it was first announced in July but here's an extract from and link to the Grauniad article about it.
Managers will receive red and yellow cards this season in a bid to clean up touchline behaviour. Although Premier League managers will only receive verbal cautions for “irresponsible behaviour” in the coming campaign, in the FA Cup, Football League, Carabao Cup, EFL Trophy and National League, they will be shown cards.
EFL Managers to be shown cards