I am logged into way too many sites to do that unfortunately. I do use a password manager with a browser plugin to make it easier, but it's still a lot of manual work to re-login to all the sites I use on a normal basis, for both work and home, every time I restart my browser.
Would be nice if there was some other solution, like maybe encrypting the browser profile and then requiring a pin/password/biometric/something to unlock it on each start.
There's a Cookie AutoDelete plugin [1] that cleans up cookies, cache, etc for a site after all of its tabs are closed. You can exclude sites that you want to stay logged in to.
Many sites I use force email or SMS-based 2FA, sometimes in addition to "security questions" and/or have other multiple steps of authorization (like captchas) required; it's often not just a simple username/password for me.
Now multiply that by 25 different sites. Not happening.
One option for that is to use multiple Firefox profiles. The main general-purpose browsing profile would have a hardened configuration, while dedicated profiles are used for other websites that should remain logged in.
Would be nice if there was some other solution, like maybe encrypting the browser profile and then requiring a pin/password/biometric/something to unlock it on each start.