Perhaps try something like this?
- name: hostname and selinux mode
ansible.builtin.lineinfile:
path: /tmp/output
line: "{{ line }}"
create: true
vars:
line: >-
Hostname: '{{ ansible_hostname }}'
{% if ansible_selinux['mode'] is defined %}
Selinux mode: '{{ ansible_selinux['mode'] }}'
{% else %}
Selinux mode: false
{% endif %}
{% if ansible_selinux['status'] is defined %}
Selinux status: '{{ ansible_selinux['status'] }}
{% else %}
Selinux status: false
{% endif %}
delegate_to: localhost