In general, freezing won’t change the weight of the water. In general.
In actuality, however, the freezing process by which liquid water gives up its heat until it reaches a freezing temperature (which is, after all, what is happening) generally occurs as some water vapor evaporates as the heat radiates from the water. So some volume of water is lost, depending on wind and weather conditions (while outside) or the operation of the refrigeration equipment (in a freezer). In addition, as the water stays frozen and the environment does not stay static – no matter how it appears to you, because you can’t sense all of the subtle environmental changes – some additional volume of water is lost via continuing evaporation and transpiration. That is, the ice gradually undergoes a phase change from solid to gas (water vapor) without appearing to melt. (You can see this happen very gradually to ice and snow during winter in northern latitudes during long dry spells after a snow or ice storm. The ice and snow don’t “melt”, but they do gradually disappear through the weather.)
But for all intents and purposes unless you’re being highly precise, “freezing doesn’t change the weight” of water.
What does happen, however, is that the ice expands the volume of the water. You already know this, right? So what has happened is the density of ice is less than the density of liquid water, which is why ice floats.