Is a Cover Letter Important with Your resume to Get a Job?

I recently submitted my resume for a job I really wanted, but I didn’t include a cover letter. My friends told me that cover letters are really important, and now I’m starting to worry. They said that a cover letter helps show your interest in the job and gives you a chance to explain why you’re a good fit and they suggested I get a professional cover letter writing service from topresume .
I thought my CV was strong enough on its own, but now I’m confused if I missed an opportunity to stand out. Have any of you ever submitted a CV without a cover letter? Did it affect your chances of getting hired? I’d love to hear your experiences and any advice you have!