how to get pure antimony from white powder antimony(III) oxide (Sb2O3) ? i need the metal itself for another experiment?

unless you want to go through a lot of trouble and you have a good lab, you would be much better advised to buy the reagent from a supplier. Antimony can be smelted (produced by thermally-enhanced reduction) from the oxide (stibnite) but it is difficult and requires fairly controlled conditions. Aqueous processing at room temperatures will not result in Sb metal as a precipitate. The stability field is barely a sliver at the very bottom (low Eh) end of the water stability field. this suggests that electroplating would be useless as well, unless you want hydrogen gas.

I suppose you could always reduce to Sb3- and form some sort of antimonide salt or sulfosalt and go that route, doing a partial oxidation to get back to Sb metal, but that is complicated as well.

Buy what you need. Save time, effort, money, instead of reinventing the wheel in your own lab.

I'm not sure, sorry.