I am a bit puzzled. You write that you currently have a SYD-SIN in February 2026.
Does that mean that your ticket is SYD-HKG-SIN on CX.
If so, you run the risk that CX in SYD will check through your luggage to SIN.
If that is a typo and you meant SYD-HKG, then it is plenty of time. However, February 2026 is very far away and schedules have a chance to change.
You seem to mention that you need a visa to get into Hong Kong. Then you'd better get one for the first flight SYD-HKG on a separate ticket.