It's impossible for you to use electrum for a transaction that has no RBF support once you have broadcast your transaction. You can use CPFP. It's there in Electrum wallet in order for your transaction to be added to the next block. Electrum can be used for transactions that supports RBF to increase transaction fee.
The is full RBF.
This amwser to question can be found here:
Re: Turn non-RBF transaction to RBF enabled?I have not bump fee with full RBF before.
I think CPFP will be good if the transaction has change.
Your only way now is CPFP(child pay for parent).
Only if the transaction has change.