(1) Should I just swap it with some StableCoin, e.g., USDT, assuming this should be not as volatile as other forms of cryptocurrency, hence a 'safer' option, before cashing it out at a CEX for $$?
This is the safest option if you just want to retain and maintain your profit and you are not a risk-taker
(2) Or should I try to identify a cryptocurrency that has a very good trading volume, and seemingly good prospects in the (near) future, yet currently at a historically lower price? And hold till the price goes up before cashing it out?
If you are a risk taker and always on the look for tokens or coins with good potential in the market this is a risky move but will pay off if you're lucky and you picked the right tokens to trade.
(3) Or is it as simple as always just swap to ETH or BNB depending on the network, as someone pointed out to me in another trading group?
Eth and Binance price is always stable in the market if you're planning to hold for the long term these two tokens are worth trading on the token where you made profits.
Whatever decision you make be sure to dig deep to maximize your profit.