AFAIK, Electrum always take fee from the funds left not from the specified amount so if you want to send any amount including fee then subtract the fee that you can see while sending.
Electrum wallet has options for transaction fees: Preserve Payments; or Decrease Payments.
It's only when bumping the initial TX but not while creating a new TX, but that's what OP is looking for so I ignored the preserve payment option while bumping.