---
- name: Check NetworkManager.conf exists
  stat:
    path: /etc/NetworkManager/NetworkManager.conf
  register: result

- name: Unmask NetworkManager service
  command: systemctl unmask NetworkManager
  when: result.stat.exists

- name: Add dnsmasq to network config
  lineinfile: >
    dest=/etc/NetworkManager/NetworkManager.conf
    regexp="dns="
    line="dns=dnsmasq"
    state=present
  when: result.stat.exists
  notify:
  - restart network manager
...