Using ActiveRecord::Callback and wrapping your create with a transaction will execute your after_create before the transaction finishes.

harmful_callbacks.rb

class User < ActiveRecord::Base
  after_create :send_welcome_email

  private
  
  def send_welcome_email
    UserMailer.welcome_email(self).deliver
  end
end

User.transaction do
  User.create(email: '[email protected]')
  sleep 10
  raise ActiveRecord::Rollback
end