In general, blatantly off-topic is only available when flagging to close but not when voting to close¹. As users with the close privilege get shown the close-vote dialogue when trying to flag to close, this means that this option is not available to them at all¹. Once you have the close privilege, you have to use another close reason or a custom close reason instead (which you can then word identically)¹.
The close reason shown below a question is that chosen by the majority of the close voters. As they cannot choose blatantly off-topic, you will never find a question closed with that reason. If the majority of close voters opt for a custom close reason, you get:
This question does not appear to be about [scope] within the scope defined in the help center.
but without blatantly off-topic.
Once closed, users with the trusted user privilege can vote to delete them; two days later, users with the moderator tools privilege can do so as well. Moreover, after a week, automatic deletion mechanisms apply.
At any time (before or after closure), diamond moderators can instantly delete the question, which is particularly likely for blatantly off-topic questions.
There is no mechanism, however, that instantly deletes such questions after closure.
¹ except on those sites which have a similar site-specific close reason, e.g., Meta SE (this very site)