Color ramps examples
The default color ramps provided by the plugin are extracted from R package biscale and can be seen at this vignette.
There is couple of bivariate legends prepared directly in the plugin and available from Color ramps: option. These should be tried with different color mixing methods, to find the best one for each bivariate color ramp.
Examples
Some of these may not look best here, as they are all exported with the Darken Blend mixing method, which may not be ideal for every color ramp.