From version 11.4, WonderPlugin Carousel supports selecting posts by tags, so you can display posts by tags in all categories or a selected category.
In the Add Posts dialog, you can select a category or All Categories from the "Select Posts" list. If you select the option "Recent Posts", it will select all categories and order the result by post_date.
You can then check the option "Select posts by tags" then enter a list of tag slugs to the following input box.
To select posts that have "either" of these tags, enter tag slugs separated with comma, for example:
To select posts that have "all" of these tags, enter tag slugs separated with plus, for example: