Q.pruning dieffenbachia
My dieffenbachia has become ‘leggy’ over the winter months indoors. Can I ‘prune’ it to encourage bushy growth? If so, is it okay to cut the main stalk? It is almost 3 feet tall. It spent last summer outside in a place where it was shaded a good deal of the day with strong sunlight in the late afternoon. Since it did well, I have moved it outside again this summer.

https://www.gardeningknowhow.com/houseplants/dumb-cane/growing-dumbcane-dieffenbachia.htm
https://www.gardeningknowhow.com/houseplants/hpgen/propagating-houseplants-from-cane-cuttings-and-divisions.htm
You can cut back your Dumbcane and then grow a new plant from the cutting.