Bank Account / Visa / Master Card -> CEX (Centralized Exchange) i.e: Binance, Kraken, etc
Buy ETH on CEX with your preferable amount
Send your fund to your DEX Wallet (i.e Metamask, Rainbow, Rabby, Zerion, TW, dll)
Before sending your fund, make sure to choose BASE CHAIN (if your CEX support it)
If your CEX doesn't support BASE CHAIN, send it to Optimism or Arbitrum Network to save gas. We will do Bridge.