Magic is a force that works subtly in regards to the physical, and does not break the laws of the universe or the laws living organisms abide by.
Physical shape-shifting is not possible. For one, magic doesn't work that way. Secondly, there are issues like conservation of mass, the amount of calories needed and the tempturture spike in a biological body from shape shiftng, how DNA functions and it's limits, how most of our mass is gut flora specific to human beings (bacteria), how the body would die the shock, etc.
As cool as it would be to be able to turn into a wolf, it literally cannot happen.
Now, actual lore and practices that we know of indicate that shape-shifting is possible through the non-physical.
The wolf shamans and warrior of the vikings, the shamanic practices of the Scythian, Irish, and others had associations with sending their forms into wolves or invoking the spirit of the wolf. The Magyre wolf-wizads, The weewolf cult of Livonia, The Brotherhood of the Green wolf in Normandy, and the Ryewulf of Germany, or the Booger dogs of Wales. We see similar practices and beliefs in the shamans, medicine men, and wise men of indigenous cultures today.
The werewolf was not men and women physically turning into a wolf or beast. Rather, it was them invoking a wolf spirit into their body, or sending their spirit out in the shape of the wolf.
The wolf witchery seems to be initiated with a symbolical death of the initiate (common to shamanism), and the use of certain items, words, and/or substances to allow a shift of consciousness, trance.
Commonly, lore states that this is a wolf-skin belt, other times it was chanting with a hallucinogenic flying salve made of herbs and wolf fat to bring hallucinations to alter the perception of the witch. These magical practices were used to bring an altered state of mind rather than actually bring about physical change and were rooted in animistic cultures.
These wolf trances would essentially send the etheric skin out in the shape of the wolf, and bring the primitive and animalistic lower self to awareness or bring in a spirit to connect these selves. It was also said in some of these Indo-European cultures that psychics, seers, and other gifted individuals could sense or see when these spirits of wolf witchery were out and about in the world.
Many gods and spirits are well known for associations with wolves or shape shifting. Odin is well known for an association with both.
I recommend you research these methods and practices, understand what shape shifting is and is not. And if you are serious enough, pursue them. This isn't just for the casual young person with an short-lived interest or curiosity in witchery or magic to sate their desire to be a wolf.
Best of luck.