As I said in my previous post, the transaction fee doesn't depend on the amount of bitcoin you send. In the other words, it's not that you pay a percentage of sending amount as transaction fee.
If you make a transaction to your friend with the same fee rate as your previous transaction, your friend will receive 0.2999927 BTC.
Even if you set the fee rate to 10 sat/vbyte (which is now much more than enough), you will pay less than 2000 sat (around $2 worth of bitcoin).
Don't worry about the fees.
According to your previous post, you are going to make a transaction from a legacy address to a native segwit address.
If that's the case, your transaction (virtual) size will be around 190 vbytes and you will pay around 190 vbytes * fee rate (in sat/vbyte) as fee.
For example, if you set the fee rate to 2 sat/vbyte, you will pay around 380 sat as transaction fee.
To know how much fee rate you need to use for your transaction, you can visit
mempool.space and you can also use electrum's own fee estimations. Both work well.
I've been meditating on that and I think I'm starting to understand, so on the mempool main page the green example blocks showing the sat, btc amount, and approx transaction time... Then below that is shows transaction fees (no priority, low priority, medium priority, high priority) with the sat v/B under it, but I don't understand the dollar amount they show with it and how it relates to my specific situation (i.e. right now it shows medium priority 4 sat/vB is $0.58).
For example, using your example above, if it was 4 sat/vB and I paid 760 sat as a transaction fee, how much would be deducted from 0.3 BTC?