When an introductory word of a noun clause is not part of the clause our can be treated like an expletive?

When an introductory Word of a noun clause is not part of the clause, it can function similarly to an expletive, serving primarily to introduce the clause without contributing to its meaning. For example, in the sentence "It is important that you arrive on time," "It" acts as an expletive, while the actual noun clause "that you arrive on time" conveys the core idea. This construction emphasizes the clause's significance rather than the introductory Word itself.