crypto average transaction fee

[Cantoner]

Hi, I am a crypto beginner. Since the bank transfer and e-wallets become harder now, I think i am gonna use crypto to deposit and withdrawal. But I am not sure how many % transaction fee is to
1. convert USD to crypto
2. crypto to eur/gbp/usd in bookie balance
3. eur/gbp/usd into crypto for withdrawal
4. crypto back into USD

it seems costing quite a lot.
The probable crypto I would use are USDT. Bitcoin and Eth also considered

Thanks!