No, Hogwarts, the fictional school of witchcraft and wizardry from J.K. Rowling's Harry Potter series, is not located in a different dimension. According to the books, Hogwarts is situated in the United Kingdom, hidden from Muggle (non-magical) society by powerful enchantments. It exists within the same physical world as the rest of the Harry Potter universe.
Hogwarts is described as being located in Scotland, in the Highlands near the lake called Loch Ness. However, its precise location is kept secret and concealed from Muggles. The magical community has various methods of hiding and protecting their world from the knowledge of non-magical individuals.
While Hogwarts and the wizarding world possess magical elements and abilities that are not present in our reality, they are depicted as being part of the same world and dimension. The stories of Harry Potter take place in a parallel universe or a hidden magical society within our own world, rather than in a separate dimension.