I have a multicurrency account with HSBC in Australia. Up until today rates usually changed a maximum of a few times per day - now you can pick the exact point and rate at which you want to convert
https://www.hsbc.com.au/1/2/misc/get-rate-pib
I don't know if this is a worldwide thing, or just HSBC AU.
I converted some USD to AUD a few moments ago. After letting the first quote lapse and refreshing it I noticed it was going downwards (which for USD-AUD is good), so I did a couple more refreshes until it went back up again, then accepted. Made about $5 extra from that small wait.
One gotcha: the amount you specify to transfer is now in the DESTINATION currency, not the SOURCE currency. I wanted to convert $USD1250 to $AUD<whatever> but ended up getting my AUD account credited with $AUD1250. I didn't realise this had changed until after the transfer was completed.