In the Time Trial Packet when looking at the Assists the document Data Output from F1 24 v27.2x states:
uint8 m_tractionControl; // 0 = off, 1 = medium, 2 = full
uint8 m_gearboxAssist; // 1 = manual, 2 = manual & suggested gear, 3 = auto
uint8 m_antiLockBrakes; // 0 (off) - 1 (on)
However in F1 24 (version 1.18) it only seems to detect on or off.
uint8 m_tractionControl; // 0 = off, 1 = on (medium/full)
uint8 m_gearboxAssist; // 0 = off (manual/manual & suggested gear), 1 = on (auto)
uint8 m_antiLockBrakes; // 0 = off, 1 = on
I think the documentation needs to be updated.