How the amount you receive is calculated
The formula is simple: received = (amount - network fee) x rate. The fee is charged not by the exchanger but by the network or the exchange you withdraw from. An exchange has its own withdrawal fee per network; from your own wallet (Trust Wallet, Ledger, MetaMask) it is the network fee itself.
Network hint after choosing an exchange
Pick an exchange in the search settings and a card "Via ... you receive +X" appears above the list with a "Go" button to that network's direction. If you are already on the best network, the card says so. The "All networks" button opens a table: network, fee, received, gain. The same button is on every exchanger card.
The "Best network" block
Another view of the same idea: a collapsed block above the list with the best network and the gain in its header. Inside there is a "Sending from" switch and network cards tagged "best" and "current". Clicking a card opens that network's direction.