NRaas Traveler is the one that allows weather/seasons in foreign worlds by default. It can be switched off entirely if it's not wanted on the NRaas > Traveler menu on the map tag of Base Camp (standing in for City Hall since WA worlds do not have those). Allowing or disallowing the individual seasons and setting the lengths can be done within the built-in Game Options as the Seasons related settings are world-specific.
The mod that can disallow the ice cream truck on a per world basis is NRaas Traffic, with the mod menu again showing on Base Camps where there is no City Hall.