How do I convert variants of one type to another type?

Here we build on this tutorial and also use the example from the tutorial "What are variants on products?"

If you work with variant types, you can also quickly convert all variants of one type to another type. You do this by using the action "Bulk change type of variants".

In the pop-up that opens, you can convert all the variants of one type to the variant of another type. For example, you can convert all shoes of size 40 to size 42 in a few clicks.