This is a good start! If you're looking to refine it a bit, maybe you could add a little more detail about how these differences between the novels actually affect the themes you're discussing. For instance, something like this:
“Both novels explore isolation, but they do so through different character journeys and settings, showing how personal struggles and the environments around them shape each character’s experience of loneliness.”
This version just adds a bit more clarity on how you’ll connect the two novels and gives the reader a better idea of the essay’s focus.
Overall, your thesis works well. A few tweaks could make it even sharper and give a clearer preview of what’s to come in your essay. Great job so far!