To deposit funds into your eToro account, you can use a variety of payment methods, including bank transfer, credit/debit card, and e-wallets. If you are looking for the cheapest and safest way to transfer funds, then a SEPA transfer to their EUR account is a good option. When the money arrives, it will be converted to USD at the current exchange rate.
If you are concerned about fluctuations in the USD exchange rate over the long term, then you may want to consider hedging your position by investing in other currencies or assets that are less affected by currency fluctuations. You can also consider using a currency hedging strategy to protect yourself from currency risk.