SnowAccumulation

1.15.2 version of this mod: https://www.curseforge.com/minecraft/mc-mods/snow-accumulation

From that mod's page:
Snow layers are incremented during snowstorms until they reach a full 8 layers. Snow next to full blocks stacks faster, making a smoother landscape. Snow stacking is related to the average neighboring snow height as well, again adding to a smoother landscape. Snow is less likely to accumulate next to non-cube blocks such as open space or fences.