You can also try the Hammer Strength Dip Machine if you have access to one, especially if you start progressing into much heavier weights and don't want to bother with belts and chains (or dumbbells between your legs).

You could always switch to doing harder types of dips.

A straight bar dip is substantially more difficult than a parallel bar dip. Due to needed to curl yourself around it like a C to balance, it also hits the chest hella hard. Smith machines work great for straight bar dips.

Ring dips are the same way, especially done in an L-sit.

These both can be further made more difficult by dropping the elbows when in the hole, shifting from upper arm parallel to lower arm parallel. Have to go slow with this, only little bits of the ROM at a time, could be very rough on the elbows at first since its such a huge load on the triceps at an extremely bent elbow angle.

And if you are strong enough, you can do planche pushups in a dip station. Instead of leaning forward a little bit to do a chest dip, lean forward a lot, so that your hips are at the same level as your shoulders, and hold your back parallel like that throughout the rep. Takes a ton of chest/shoulder strength to even hold the rotated position. Kinda like a super chest dip. Tucking your knees into your chest makes them easier, but even the most basic variant is a very advanced exercise.