[Vuejs]-How can I send data from a child component to a child component without using props?

What you want is called event bus in vue.js, but it is an anti-pattern so it was removed from the API in vue 3.

However if you really liked that approach, you can probably achieve it with an external library that implements the event emitter interface.

You can read more about it here with provided example: https://v3-migration.vuejs.org/breaking-changes/events-api.html#event-bus