Scientists quite often misrepresent the theory themselves, often referring to something evolving this or that in order to better cope. That is total nonsense.
If evolution is 100% accepted, it is still not a guided change.
The most that can be said is that things change, if that change does not preclude them from the surviving. There is no logical reason to presume that giraffes needed a longer neck, as short necked ruminants have done just fine. The most that we can say is that giraffes evolved to have longer necks, for reasons we cannot presume to understand, and that they have survived that change. We have no idea whether the giraffe is better off as a species by having a longer neck, we just know that they do have longer necks, and they have survived.
the neck of a giraffe can be explained by natural selection. less competition for leaves at those heights on a tree gave giraffes a better chance of survival.
what can’t be explained is how/why a fish evolved into a giraffe. that’s where evolution makes the leap to untestable theory.