Can we I identify crypto-exchange (BTC) hot wallets?
it really depends. Some exchanges have their addresses labeled in services like Blockchain.com and so on. I believe they share with them the Xpub so they can map all of them back to the exchange.

Not all exchanges have that. 

I've tried to do that once and gave up because the quality of the data available on which exchange controlling which addresses is really low. Additionally some exchanges (I don't know how many nor which) do these interexchange transactions using the Liquid side chain. Maybe some of the blockstream guys hanging around can illuminate my answer here

So, unless you have direct access to the exchanges' Xpub or some good data source on labels, it's really hard to do this type of analysis