Many Android phones are not secured by default. If you have an android phone that’s not an official Google phone (like the Nexus or Pixel series), it’s unlikely you are receiving timely security updates, and they may not be available to you at all. Without these critical updates, your phone is more vulnerable.
The following steps are still important to take, but they will not protect you as well as they could if your phone is not up to date. Mark sure you have installed all updates.