Use a vpn with a Eu server. More sites like google will show a cookie popup with the “reject all cookies” option.
Reject all cookies if it exists. Otherwise accept cookies and then click on the :
shield icon > cookies and site data > delete (trash icon)
This is super useful when you want to read an article on some news website and it shows a cookie popup.
From my tests none of the privacy browser are that good at privacy, I tested with https://coveryourtracks.eff.org/ and some either have unique fingerprints or partial, while also providing other data useful for fingerprinting, with one exception being Mulvad browser that has the best score, all tested with JavaScript enabled, turning it off will stop a lot of data from being provided but will also break lots of sites.
I was thinking more along the lines of either obscuring system clock or changing it entirely as far as the apps or web browser can see. Say, making it so that it matches the time zone of your VPN.
I’m not sure there’s a way other than manually, maybe you could set multiple timezones in the clock app and check the one you’re in