How can I add more than one server-type context?

You add the perm multiple times, each one with another context

Can you send me an example of the contexts.json ?

There's an example here.

https://github.com/lucko/LuckPerms/wiki/Context#defining-static-contexts

If you want to add more, do so like this:

{
  "static-contexts": {
    "server-type": ["skyblock", "normal"]
  },
}