Since decentralized exchanges do not require verification, you should use the Dydx.exchange, where margin trading is available.
I don't know about margin available or not in DEX, but surely DEX doesn't require KYC. There are most trusted DEX can be used, why did you choose Dydx?
Uniswap or Pancakeswap, I think these DEXs are most famous than Dydx. Regarding margin, what I know so far, it is one of the features we can get from CEX, such as in Binance, top exchanges. Is DEX having margin as well, bro?