Normally users enter the amount which they want to sent and specify a fee which comes silently (!) on top.
So what if I want to sent a certain exact amount INCLUDING the fee?
Is Electrum somehow able to
recognize my offered fee Sat/vbyte,
+ calculate to total fees amount,
+ subtract it from my total amount
+ send only the remaining amount to receiver?
How does that work?
You don't need to calculate the fee, you can use
https://mempool.space/ to check the fee needed for your transaction. Also you can use the fee slider to adjust your transaction fee.