I understood from the video I could install and issue client-side commands to have my own Player Character do a thing (use continuous and attack continuous) without needing Carpet installed server-side, is this still supported in 1.16.x? if so how do I do this?

I'm almost sure it's the other way around. You can do that without having carpet in the client side, but in the server.

I tried typing "/player JohnyDL Attack" into my client with the mod installed which should be enough to keep sending to the server for my PC to do that action over and over I get that I can't spawn other players in to do things without it being server side but the way I understood the explanation was that I can do it instead of having to you know run an auto hotkey script and be unable to use my PC

the command is /player JohnyDK attack continuous, and you have to type /player JohnyDL shadow for the server to do actually do it, cos it doesnt always work. But that only works on a server.

yeah, and the comands are all listed in the video. Those that aren't are so simple they dont need an explanation.

Yeah and they run core protect and all sorts of other things, if it was one click they'd switch in an instant but since it isn't they're not willing

ah so I do need the server side ... damn... the server runners aren't willing to install carpet for me (apparently not compatible with spigot/paper something... I wasn't listening)

yeah, it isnt

tho tbh carpet provides a lot more performance improvements that paper/spigot, and with scarpet you can recreate most plugins...

But that requires to have a dev, who wants to recreate all plugins from scratch in Scarpet, and who probably want to be paid.

carpet is a primarily a server side mod. There are no plans of making fake client side players or controling client side players on servers with local scarpet.