Do SEOs implement the changes?

Hi,

This might sound lile a dumb question but let's say I habe an SEO optimization company. I do an audit of a site and prepared the changes that I want to do for the site in order to optimize it. Do I actually make the changes in html/wordpress etc or do I talk to the client and he passes on the optimization tasks to the developer or the company that made the website?

I am currently working for a medium sized company in SEO and would like to slowly transition into freelancing and getting some clients on the side.

Also any tips would br aplreciated.

Thank you in advance.