Can a user edit their answer when filling out lead fields (name, phone number, email, etc.)?

Yes, absolutely!
End users can always go back and choose multiple-choice options.
Also, free text response has a "pencil" icon that allows end users to edit their responses.
When a user clicks on that icon the bot repeats the step for requesting the user to input a new response. See an example in the video below.

Using the “pencil” icon relies on the end user's understanding this can be done in the bot.
But if you want to have a double-check, you always can add a multiple-choice node for checking if the information entered by the user is correct. The multiple-choice node would have two possible options: Yes or No. If the user selects No, the bot will return to the previous step for requesting the user answer again.

In addition, the email type node provides a validation of the general format of email addresses (prefix@domain). If end users input an invalid email format, you can customize the message to show users while requesting them to re-enter the email.