if you are using Odoo in docker, then its best to use the wktmltopdf in docker as a service 

  wkhtmltopdf:
    image: odoo:16.0-wkhtmltopdf

otherwise, you will have to access the binary from Docker odoo, which may not be efficient.  The wkhtmltopdf binary should be accessed via this line in odoo.conf

[options]
; Set the path to wkhtmltopdf binary
; (Ensure it matches the path used in your Docker image)
wkhtmltopdf_path = /usr/local/bin/wkhtmltopdf