How can I create a lead with new contact and new account for a sales prospect?

By default, the leads pages display only names of accounts and contacts that already exist in the application.

If you want to create leads for new accounts or add new contacts, then you must create the appropriate account and contact records before creating the lead.

If your business uses net new leads where contact and account values are entered manually using free form text fields, then your administrator can make the New Account and New Contact fields available on the Leads UI through Application Composer. These fields are hidden by default so to use them for your new leads, your administrator must manually unhide these fields.