To add to the comments, most distros do not offer FDE by default when installing. You have to jump thru hoops. No idea why this is still the case given how many consumer computers are laptops these days, it seems crazy.
The big exception seems to be PopOS, an Ubuntu derivative which is intended for laptops. FDE by default so it must be pretty easy to get that up and running.
Ubuntu itself has a solid FDE option on install, too. It sets up the LVM configuration as already described, no expertise needed. And IME works very reliably.