(Former CTF hobbyist here) You might be mixing up XSS and CSRF protections. Cookie protections are useful against XSS vulnerabilities because they make it harder for attackers to get a hold on user sessions (often mediated through cookies). It doesn't really help against CSRF attacks though. Say you visit attacker.com and it contains an auto-submitting form making a POST request to yourwebsite.com/delete-my-account. In that case, your cookies would be sent along and if no CSRF protection is there (origin checks, tokens, ...) your account might end up deleted. I know it doesn't answer the original question but hope it's useful information nonetheless!
SameSite=Lax (default for legacy sites in Chrome) will protect you against POST-based CSRF.
SameSite=Strict will also protect against GET-based CSRF (which shouldn't really exist as GET is not a safe method that should be allowed to trigger state changes, but in practice some applications do it). It does, however, also make it so users clicking a link to your page might not be logged in once they arrive unless you implement other measures.
In practice, SameSite=Lax is appropriate and just works for most sites. A notable exception are POST-based SAML SSO flows, which might require a SameSite=None cookie just for the login flow.
You usually need another method as well
In practice, SameSite=Lax is already very effective in preventing _most_ CSRF attacks. However, I 100% agree with you that adding a second defense mechanism (such as the Sec header, a custom "Protect-Me-From-Csrf: true" header, or if you have a really sensitive use case, cryptographically secure CSRF tokens) is a very good idea.