Yes there are some dex or platform who provide bridge conversion, mainly those who has a lot of multichain assets like RSK for example. If you can list what assets you're using it will be easier to find which one you can use. I heard Liquality is quite good if you're dealing with ETH and BNB (BSC) quite often. Keep in mind that the fees might be way higher than CEX, mainly because ETH network is such a pain in the ass lately.
Binance Chain is a fork of Ethereum, the bridge is trivial, it is also possible to bridge to AVAX and Ethereum. Probably Polkadot will also have greate integrability with Ethereum variants( not sure).
It is relatively easy to develop a very especific solution to bridge two pair of specific coins, but it is very restrictive, and it looks like that there are no such solution to integrate lots of blockchains. I know, it is a hard problem, may be impossible without treat each pair of coins and build a specific bridge.
Thanks for RSK, will research into, interesting.
You will have to go on several DEX to convert because ADA and SOL are two different platform tokens as well which have their own DEX. There are many ADA dex, I'm not sure if they are working already and so are for SOL, they have their own DEX. For BTC and ETH, I would use the WAVES dex.
Will look into WAVES, thanks.