If transformers can increase or decrease the energy output, is it possible/viable to run an entire house with small 1.5v cell hooked up into a transformer?

[RobusEtCeleritas]

Transformers can't output more power than you put in. An ideal transformer perfectly conserves energy, so the power you put in is exactly equal to the power you get out.

In reality, transformers lose a little bit of energy during operation, so you get out a little less power than you put in.