Hope you start by getting your body proportions/measurements. Here's a quick guide.
https://www.sierra.com/lp2/bike-fit-guide/
some notes - when doing the 'inseam' measurement, make sure the book is Firmly up your crotch ! (a 1" , 2-3mm binding works well), bare feet.
torso - some may measure to to the V in throat, I measure to the boney prominence at the back base of neck - either... Easiest is to measure floor to throat/neck standing straight, then subtract the 'inseam' measurement derived before - that difference is the torso length.
Arm length - I like to measure from the distal (outer end) of the collar bone to the Syloid process (wrist bone). Of course we all have differing hand lengths, but that can be adjusted for.
As Iride01 states - 'setup' guidelines are just starting points,, from which you might go further.
Your own body flexibility, strengths & weaknesses, how you carry your body mas/weight all work into how you adjust, along with what purpose your riding is focused on...
Ride On
Yuri