That depends on the exchange you want to get listed on. There are several exchanges around that are actively looking for almost every new project to list. Bilaxy for example is sometimes listing new projects even if they don't ask for it. To get listed on the big exchanges like Binance, Coinbase or even Kucoin is not that easy as you have to pay a lot of money or you need be a really big or hyped project already so that those exchanges don't want to miss out on the trading fees. Of course nowadays there are also alot of DEX'es around like Uniswap or Pancakswap where you can basically list your project yourself.. you just need to provide liquidity for the trading pair.