You’ve not given any context for why you want this modelled and how it’ll be used. You say you’re happy to pay someone but it doesn’t really make sense to pay someone to give you a tutorial on this specific thing. If you need something high quality for a 2d/3d print then you’re probably best just paying to commission someone to make it for you. It’ll be quicker and cheaper this way.
If you do really want to pay someone (assuming you have a proper budget) to show you how to model this I’m sure you can find someone. I think there’s a member on here who models the Pokemon characters that offers that sort of thing.
But if you’d like to model this as a way to learn Blender Omar’s point is valid. Instead of buying a fish, teach yourself to fish. This isn’t a particularly large or complicated thing to create. What do you know how to do? I look at this and see 3 main areas
The chain
The locket
The sculpted pet portraits
You will find youtube tutorials for all of the above. The pet portraits look personal / sentimental e.g. you don’t want to model just any dog & cat but want the likeness on the actual locket? This will be harder to do. An alternative solution would be to get high resolution photos and try and use those as a bump/displacement map again it depends on what you’re intentions are for the model.
The first thing to do is assess how much you can simplify/stylise the model and if you could do it if that’s the case. If you don’t know how do it as a low poly model like shown below then either just commission someone or you’re better off starting on something more basic
