sure! https://forum.xda-developers.com/mi-a2-lite/how-to/guide-how-to-unlock-bootloader-erasing-t3878453
Just be sure that you reenter fastboot after rebooting - by pressing vol-. Then it won´t erase your data.
To be fully sure boot twrp, install it, flash aboot from 9.6.11.0 - else you will get "your system got destroyed" while booting twrp and then you can save your data partition to external sd card - now even if it would try to erase your data, you will have a backup.
And after reboot you will see, if it still tries to erase data - then it will go again and again to twrp... To solve that, reflash stock kernel - just in case.