It is quite possible that you will not find something as specific as an SEO organization, whereas you might find material suitable for a manufacturing company, for example. However, the point here is that every organization is different. You need to write manuals specific to your company and its policies and procedures—which will be different from other companies' policies and procedures.
So, on that basis, you can use manuals that other members have posted here as a guide to content, format, and layout, and adapt them to suit your requirements. If you want someone else to do your work for you, I would suggest employing an HR specialist to come in and write your manuals.
In the time you have taken to post a query, wait for answers, and now debate the issue with me, you could have found some sample manuals on CiteHR and be well on the way to having the first draft of your manual written. All I want to do is encourage you to use the fantastic resources you have at your disposal here on CiteHR and adapt where necessary to meet your organizational requirements.