Q: Can I cut and paste my cover letter into multiple online job applications?
A: You can, but then make sure to go back and customize each letter at least a bit, using the information from the posting, the website, or anything else you may know about the particular employer. Rather than submitting a boilerplate letter, and without making it too long, give a nod to the skills and tasks for the role, the culture, and/or a core trait or two emphasized in the job description.
Don’t just plug in key words as if only a robot is screening candidates. A meaningful cover letter can be of value, as long as you write one worth reading by a busy person. Don’t write a novel, but quickly try to make each submission novel.