I'm still new to lifting but I've come across a lot of pages advertising for example Chris Hemsworth's workout program or Chris Evans etc.
I understand that they're likely not showing the real program they used but what I'm wondering is: whether there are secret combinations of exercises or if the super professional people are at the end of day also just using The GZCL and similar programs, obviously in combination with 'roids in many cases.
There are no secret workouts.
The beautiful demigod beefcakes known as Chris Hemsworth and Chris Evans (and for that matter, Chris Pratt) have personal trainers who tailor their every workout to their exact needs. No program. Just different workouts depending on the current short-term goals.
Need a bigger chest? We're adding this exercise to the plan.
Need bigger arms? We're adding that exercise to the plan.
Need to adjust the shoulder-to-bicep ratio? We're adding this exercise to the plan.
Need to do a photo shoot in three days? We're removing these items from your diet.
Need to shoot a topless combat scene next week? We're doing these workouts until then.
Again, they don't have a workout program. They have a group of trainers telling them what to do every single day based on a series of ever-changing short-term goals.
The secret plans
...are bullshit. There are no secret workouts. We know all the exercises. Unless you hire a trainer, you're on your own in the task of putting them together in a way that makes sense for your specific body, and your specific goals. And with some experience, you'll be able to do that for yourself by testing different things and seeing what works for you.
Anyone claiming they have a secret training program is trying to sell you something. Even worse, they're trying to sell you a bog-standard training program that you could have gotten for free by googling "how to [my goals] for people with [my body type]". There are gonna be some bad apples in those Google results too, but every now and then you'll find something that doesn't immediately ask for your credit card info and the deed to your house.
That is one magic secret that is so blatantly obvious, no-one really notices.
You won't improve if you don't begin something. It doesn't have to be a highly focused program.
Some people are blessed, some are cursed, but every single person has to do work to improve. Once you have formed that good habit of working on yourself, improvements will come.
You can suffer from choice overload, or "shopping paralysis" where there are too many options and the desire to choose the "best" option stops you from doing anything.
You generally can't go wrong with improvements to your core - that is a good foundation for hanging more specific work off later. A weaker core makes more-targetted exercise less beneficial.
Of course rest days and light days are fine, as part of your habit. A rest day is not an excuse to undo the previous work, its a "go for a walk" day instead of a gym day.
Stopping is to be avoided where possible. Personal note - the two significant C19 lockdowns in my country lasted 6-8 weeks and that put me back. Getting going again was difficult, if I'd maintained some level of "doing something" it wouldn't be such a challenge.
There are actually 42 magic workout secrets, but if they're revealed, there'll be less and your count will be off!
That said, take a look at Wim Hof's work, which has at least been replicated by others, if hotly debated and dangerous
https://en.wikipedia.org/wiki/Wim_Hof
The essence is that systems responsible for preventing death in a healthy body can be both trained and carefully used to get more work out of the applicable systems (practically, the muscles, lungs, and temperature control loop) .. but at a cost of leading one closer to over-straining the body than is otherwise possible, potentially with dire consequences, such as blackout during activity, drowning, extreme frostbite, breakage of bone-muscle connections, excessive damage to muscles, etc.
However, this is not magic, and mostly adrenaline response
