Remove minimum number of points from pattern unlock
A quick google search for android custom lock screen presents me with a list of lock screen apps (for example this one: https://www.androidpit.com/best-android-lock-screen-apps). I don't think these apps need root access to function.

Many of these apps support "slide to unlock". Which is basically the same as a pattern consisting of a straight line, which is what I assume you want.
Most apps I saw require you to swipe from left to right on the bottom of the screen. This is a specific direction starting from a specific location on the screen, yet the pattern is incredibly fast and easy.
This prevents most cases of "butt-dialing" without giving up speed of unlocking your phone.

Take your pick from the many lockscreen apps that support this and enjoy! :)