In order to make a sizable profit with your 20 ethereum, I’d suggest you try margin trading. It allows you to multiply the return having only 20 coins. For example, a platform Cex Broker provides up to 10x leverage on ethereum and bitcoin -
https://cexbro.com/. It means that you can turn your 20 coins into 200 coins and trade them. Margin trading can be lucrative but keep in mind that the risk is higher as well. Therefore, educate yourself about this way of trading first. For every single trade whether on margin or not use a stop loss to be safer. If you need practice, the platform offers a free demo account where you can acquire the needed skills.
As for $200, I’d invest in IOTA or Cardano that I think can bring good returns. But you should DYOR on this issue because only you are responsible for any financial loss it may cause. Learn more regarding what fundamentals are and who stands behind the cryptocurrency you want to invest and estimate how profitable it can be.