If you do, then also choose full-disk encryption. It doesn't make sense to close a small hole only to leave the big one gaping wide open. And yet on Linux FDE is mostly off by default, even in today's era of encryption, even on laptops. Personally I don't understand it.

Once you're encrypted, then Secure Boot (if you even have the option of it) mitigates against the "evil maid attack". To get access to your encrypted computer, the attacker will need physical access to it twice: first to swap out the bootloader, then to harvest the password you unsuspectingly passed to their freshly installed malware.

For most targets (i.e. you, probably), this would all be far too much trouble. But technically it closes a loophole: it means that you can go to Russia as a spy or a journalist and not have to carry your laptop on your person at all times.