Since you are talking about wilderness camping, and presupposing that everyone should be following Leave No Trace, camping skills can be practiced in many places - even on public camping grounds to some extent.
If you take Leave No Trace seriously, and actually try to minimise your footprint on the area you visit this will mean...
- that you cook on portable stoves using fuel which you brought along,
- bring with you all the food you plan to eat, i.e. no foraging/hunting/fishing,
- you'll carry out all of your waste, including excrement (or at least the harder-to-decompose parts, such as toilet paper),
If this is what you are looking for then I suggest doing some test runs on public camping grounds. Since your impact on the environment should be minimal and you are in essence almost completely self-sufficient there is no real need for any wilderness.
Once you're comfortable with your gear and your setup you could go for longer overnight treks. There are plenty of areas where you can enjoy remote outdoor experiences - Scotland, Norway, Finnland, Sweden come to mind where you will find wilderness areas that are accessible for camping and trekking (as a starting point google Kungsleden for example - or ask a new question focusing on this specific requirement).
From your questions it could also be that what you might be after instead is a place where you can go and try out all the cool bushcraft and survival techniques that many YouTube channels so generously supply us with... If that is the case I'd like to state: many of the shown techniques don't generally go too well with Leave No Trace.
--> Building tools and improvised shelters from trees and deadwood, cooking on open fires and generally camping in the same spot for a longer time (say, multiple days) will leave a significantly larger footprint on the area you are visiting.
This isn't to say that there aren't some rare and valid applications for these techniques - but if you are looking for official regulation condoning such techniques you will be hard-pressed, since the prevailing trend is going towards Leave No Trace (and for good reason, I might add), and all the bushcraft/survival hullabaloo is in conflict with this to at least some degree.