The phrase "in different sizes" is correct and usable in written English. You can use it when referring to items, such as clothing, that may come in various sizes. For example, "This store has a large selection of t-shirts in different sizes.".
Comes in different sizes.
Available in different sizes.
The frames are available in different sizes.
Bundles come in different sizes, from 10too 100.
They come in different sizes and different races.
There are hundreds of PC laptops available in different sizes.
For example, power plants come in different sizes and formats.
Ludwig does not simply clarify my doubts with English writing, it enlightens my writing with new possibilities
Simone Ivan Conte
Software Engineer at Adobe, UK