Is direct tricep work needed?

Currently I am doing 531 BBB which has bench and ohp day and both of them hit the triceps but not as the main muscle. For push assistance I also do incline dumbbell press and dips which also don’t fully target triceps. Should I add in overhead tricep extensions to fully isolate triceps or will my current scheme grow my triceps sufficiently?

This will totally depend on your genetics. For me I need a lot of direct tricep/bicep work.
For others assistance type movements might be enough.
All depends on your genetics vs how you want your arms to look.
As an example, I only do 3 sets/week directly for shoulders.