Tesla MODEL X 2019 Owner's Manual page 39

Seating Children Safely
seat behind the driver's seat. With reduced clearance, the movement of the seat may impact
a child's legs, cause injury, or dislodge the seat.
Warning: Before driving after installing a child seat in the second row, ensure that a "seat
unlocked" warning does NOT display on the touchscreen or instrument panel. This warning
indicates that the seat is unsafe for an occupant because it was not returned to its safe,
locked position. If the touchscreen or instrument panel displays the warning message, move
the seat or backrest slightly forward or backward until it locks firmly into position and the
message no longer displays.
38 Model X Owner's Manual