In QuickBooks Online you can connect your bank account and credit card account on file as long as it is a supported financial institution. A credit card account is a liability account and will reflect in your Balance sheet. Make sure to set up the credit card correctly as a liability account type. The same goes for the bank account type, set up as cash and cash equivalent type, and enter the opening balance.
Once the account is set up and connected your transactions will be downloaded and ready for you to categorise and add them to QuickBooks Online. You can then reconcile your credit card and bank accounts on file making sure your books balance with your bank statements.