Add weight and lean forward to load the chest hard.
Lean forward the whole time, staying upright shifts the work to your triceps.
The weighted chest dip is one of the few ways to overload the pecs in a deep stretch with your whole body moving through space. The forward lean and slight elbow flare aim the work at the chest, the triceps and shoulders back up the press out of the bottom, and the belt or dumbbell lets you keep adding load long after bodyweight dips get easy. For lifters chasing a bigger chest without endless bench pressing, it is elite.
A dip belt is the better long-term tool, it hangs the load from your hips and stays put. Squeezing a dumbbell between your feet works for lighter loads but gets awkward as the weight climbs.
Until you feel a real stretch across your chest, then press back up. Depth is where the growth stimulus lives, so pick a load that lets you reach that stretch under control every rep.
You have drifted upright. The forward lean is what points the work at your pecs, so keep your torso tipped forward the entire set, including on the press back up.
