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.

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End user edits a response

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 ([email protected]). If end users input an invalid email format, you can customize the message to show users while requesting them to re-enter the email.