I want to trade pair Ripple\BTC, or LTC\BTC, and maybe also with cross leverage. Tell me, is there such an opportunity on Bisq? Or maybe on other decentralized exchanges?
No, you can't trade shitcoins like ripple on Bisq exchange, and there is Litecoin but there is no volume for that tradin pair right now (I guess you can always create your own offer).
Bisq is mostly used for trading fiat currency with Bitcoin or Moneor, and you can check all Bisq markets here:
https://bisq.markets/For BTC-LTC maybe you can use BlockDX, AtomicDEX, Atomic swaps or some centralized swap exchanges like exch.cx.