Yes, as with all water based paints, it is necessary to seal knots prior to painting. Any standard knotting solution is ok and does not affect the performance / application of Earthborn Eggshell.
However, if you are unable or reluctant to use a knotting solution, you could heat the knots with a hot air blower until resin bleeds out of the wood. You would need to wipe down with a solvent such as methylated spirits before painting. Dependent on the wood, this may not be a permanent treatment.