What is said upstairs is right. But who is reading your cover letter now? They all read resumes directly. You can make a cover. Then this is the cover letter, and then this is the resume.

If it's delivered online, I'll tell you to send your resume directly. Don't send any cover letters, it will affect the effect.

Some companies will indicate the addition of attachments, while others will let you send your resume directly for fear of viruses.