Would two step down transformers rated at 1000w, one plugged into the other work as one 2000w step down transformer? Considering using a 1500w 110 circular saw in a 220v household

No, you would still be pulling 1500 watts through each tranformer. You are only steping down voltage. If you step down 220 volts to X volts you would have to have another transformer to step down X volts to 110. Not two 220 to 110 transformers.