How to execute task by default, adjusting with a (not) set variable?

Question

Ansible

Good afternoon everyone!
I want to pass a variable to the ansible playbook, for example ansible-playbook -e "myvar=true" myplaybook.yml
in the playbook there are task1 and task2 tasks
how to make it so that if the variable is not set, it will be considered false by default and task1 will be executed ( default)
and if it is set to true, then task2 was executed
thanks

Answer 1

Jinja2 templates hasn't gone through yet?)

- name: Create user
  user:
    name: "{{ my_variable | default('default_value') }}"

Answer 2

In variables, define it as false by default