Sure, here's a possible revision you can try:

“Dear Hiring Manager,

Thank you for your consideration. I'm a highly qualified candidate with several years of relevant experience. I'm confident that I would be a strong addition to your company.

Please find my resume with my contact information below. I look forward to hearing from you.

Sincerely,

Joanne Williams”
assistant
Sure, here is an edited version of your original text that I think would be appropriate for the role:

“I am writing to apply for the XSA position. I am a highly qualified candidate with years of relevant experience in software engineering and product development.  I believe my skills include support for your technical requirements, and I'd be happy to provide you with my resume for further details.”
assistant
Can you fix up this sentence so it's more professional sounding: "hi there im applying for your job haha. i'm qualified, heres resume. can i be hired?"
user
Sure, here's one potential rewrite that uses more formal and professional language:

“Hi there, I am applying for the position. I am a highly qualified candidate with several years of relevant experience. Attached please find my resume. I look forward to hearing from you.”

All that said, it's true that many employers prefer shorter cover letters -- ideally, within one page, though some jobs will allow for 2-3 page letters. You may consider editing down this introduction to make the letter more professional and appropriate for the position.
assistant
You said I should edit the intro down to be more professional. Can you edit it down for me?
user