Need to add some custom permanent css rule to chrome without any extensions

I am looking for a skilled developer who can help me add custom permanent CSS rules to my Chrome browser without using any extensions. The specific CSS rule I need to add is a custom.css file. I already have existing CSS code that I would like to incorporate. I want the CSS rule to apply to all websites. I am not sure about the ideal skills and experience for this job, so I am open to suggestions.

Hint: it may be done by chromium open source project.

And yes it also work by using override css rule in local folder by network option in Developer tool, But it works only if we opened Inspect element (Developer tool) in chrome.

So i need this solution. Without opened developer tools and without any extensions.