There are only so many things you can control in life, and your genetics isn't one of them. Aside from hitting the gym and plastic surgery, you have little say over how your appearance turns out — and even then, you may have less control than you think.
Blame Your Genetics
Casting clothes, makeup, and hairstyles aside, what you see in the mirror is dictated by the unique set of genes that you inherit. Short of the kind of gene therapy that doesn't exist yet, there is very little you can do to change or control your bone structure, muscle structure, and fat distribution.
Diving into the bare bones of the matter (pun intended), your bone structure is probably the biggest — and least malleable — part of your shape. As an example of this, take Hugh Jackman versus Chris Hemsworth (Thor versus Wolverine — if only). Both are evidently athletic, but Jackman has proportionately wider hips, while Hemsworth has broader shoulders. You can't change this basic framework, but you can selectively exercise muscles to give the illusion that it's a little different.
Unlike your skeleton, your muscles are somewhat more malleable; you can build them up, or break them down as you please. That said, how they look in either state is controlled by their insertions — that is, where the muscle connects to the bone. Some people have higher insertions, others lower. In the case of your biceps, a higher insertion will make the muscle look longer but less 'peaked' (that is, rounded), while a lower insertion makes it look chunkier but more rounded. So for you pilates/barre fans out there, you can't make your muscles 'long and lean' at the behest of your instructor. How long they are was determined at birth. You only control how big they grow.
Finally, there's fat distribution. As you've probably noticed (and complained about), your body judiciously or not-so-judiciously stores fat in various parts of your body: thighs, face, arms, torso and so on. But on a deeper level, it also stores this fat in different ways. The main classifications are subcutaneous fat (under the skin), and visceral fat (around your organs).
Subcutaneous fat is the one you're most likely to notice, simply because it's more visible. It's what contributes to flabby arms and thighs, bigger butts, cellulite, and man boobs. Visceral fat, on the other had, is the main perpetrator in forming what is colloquially known as the beer belly (repping the dadbod). As you may have guessed from the general theme we have going, you have no real say over how your body partitions fat storage between the two, or where your body stores it. You only control how much fat you store in total.
Your Goal May Be Unattainable
At this point, you're probably a little mad at me for crushing your dreams. Sorry to be a downer, but the chances that you'd inherit the magical configuration of all of the above, you're unlikely to match your goal physique to a T.
That doesn't mean a goal body is worthless in your pursuit of fitness, though. It's just important to understand that it's an ideal, not a mould you need to fit into perfectly. But too often, people don't remember that. I've seen so many become fixated on the minute details of their physique — the "thigh gap" being the worst offender — that they ignore or discredit the rest of the progress they have made. It's an easy trap to fall into when it's your only standard for evaluation, and can do real damage to your motivation.
It's also harmful if you misunderstand what that goal represents. It's easy to be unhappy with your body. Ultimately, that's what usually provides the impetus for a lifestyle change. But what you need to question is whether you're looking to change it because you're unsatisfied with how you look and think you deserve to be healthier, or projecting your life dissatisfaction onto your appearance. Don't fall into the trap of conflating the "perfect physique" with the success and happiness of the people who have it. Superficial change won't compensate for emotional deficiency.
What You Should Aim For Instead
If you need to pin your efforts on something, be realistic: aiming for a Victoria's Secret body when you're built like Beyoncé is a pointless (and, we'd argue, completely misguided) exercise. Use your goal body as inspiration to stick with your efforts, instead of expecting to match it exactly. And if you can go without the visual motivation, do. The best approach is to aim for the best version of yourself. Directing your efforts inwards to build yourself up is always going to be more effective and beneficial than trying to reach for something you're not.