You can do a sidechain on:
- the volume of the bass
- the volume of a frequency band of the bass (TAP Equalizer / BW)
- the W / D of a high pass filter
- the ratio of a compressor
- etc.
Another trick would be to slightly shift or delay the bass compared to the kick, for example via ENV> VOLUME> DEL.
On an oscilloscope, if you observe separately the waveforms of the kick and the bass, you will notice that they both have a fairly intense attack, a large amplitude attack. If the peak intensity of the kick and the peak of intensity of the bass occur at the same time, in terms of millisecond, as they add up, you quickly reach the ceiling, the 0dB. By cons, if you shifts one of them a little in the timeline, you gain a little headroom. But at this stage, this type of micro-gain can only be observed on a measuring instrument (oscilloscope, dB meter, etc.).