In principle (as Google defines it), if you try to better the rankings of a website doing anything more than optimizing on-page content, then you are manipulating the search engine results. White-hat is more of a marketing term used by grey/black-hat SEOs or salespeople. There are SEOs that are 100% white-hat but not efficient, meaning their rankings suck. If you run link-building campaigns, content marketing targeting more inbound links, even if you are optimizing too much the page copy, you are at least grey-hat. So, again, in principle, every SEO out there is manipulating the rankings. The thing is what method you use that can produce results today without getting a penalty, as there are so many factors at play and changes which likely will override in the future your current method. It would be best to stay sharp, adjust your plan following the changes, and always produce results, that's my approach.