Calyxos doesn't allow root & I don't know if you can force it to root.
Discussion
magisk is the best option after rooting and restore just remove and lock your bootloader, I use kernelsu not sure if it supports + a little more on the technical side
https://xdaforums.com/t/fyi-magisk-works-on-grapheneos-and-calyxos.4473445/
You probably can