It’s important to remember that OKRs for CEO are not the same as company’s OKRs.
The company OKRs give direction to all your teams. While personal OKRs only show what’s CEOs part in getting the company OKRs done.
All in all, you don’t actually need personal OKRs for the CEO or other employees. You can have company level OKRs and Team level OKRs. CEO would be part of the leadership or executive team. And their goals would show what they are doing to help the company move towards their quarterly goals.
If you still want to use personal OKRs for the leadership, there is a great site called OKR examples. The site has a lot of examples for both company and individual teams.