Samsung SM-A11 schematic pages for the power button and volume keys, provided in a 4.33 MB PDF. You can follow each key line from the side flex or contacts through the protection parts to the PMIC or processor inputs. This helps when the phone will not power on from the button, a key is stuck or volume does not respond, letting you check for pull-up voltage and shorted ESD diodes. Opens in any PDF viewer; match the board revision before trusting part references.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @phoneSchematics. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.