Though the triceps get a ton of work from presses, dips & pushups, it’s still important to isolate them for best results. For one, they comprise approximately 2/3 of your upper arm mass so they have the biggest overall impact on arms size. In addition, the meaty long head of the upper arm is preferentially targeted by doing elbow extensions with the arms overhead because it attaches into the scapula.
Triceps Extensions can be done 3 main ways in order of difficulty: Overhead Triceps Extensions, Lying Triceps Extensions & Triceps Pushdowns. Use bands at a faster tempo to maximize the contraction phase. Use dumbbells at a slower tempo to maximize the stretch phase. I recommend going lighter for 10-15+ reps for these moves since you get plenty of heavier work with multi-joint pushing moves. Focus first & foremost on range of motion.
My favorite triceps workout stacks these 3 moves in-a-row from hardest to easiest for a fast & furious finisher. If you suffer from elbow pain, consider starting or ending your workout with 50-100 triceps pushdowns in as a few sets as possible. Bands are easier on the joints and require less recovery time.