nano /etc/default/keyboard

# KEYBOARD CONFIGURATION FILE

# Consult the keyboard(5) manual page.

XKBMODEL="pc105"
XKBLAYOUT="us,ua,ru,de,fr"
XKBVARIANT=""
XKBOPTIONS="grp:alt_shift_toggle"

BACKSPACE="guess"

no final:
udevadm trigger --subsystem-match=input --action=change

https://wiki.debian.org/LXDE#Keyboard_layout_switching