The short answer is that it depends. I would need to see the wiring diagram detail for the specific application to answer that.
Most likely though, the primary circuitry is contained within the package and would be difficult, if not impossible, to tap for direct voltage. This is often the case with may Coil On Plug systems as well. Many of these have the igniter or power transistor contained within the coil itself. On these, access to direct primary voltage is impossible. You can, however, view the IC commands, primary current, or possibly pick up the secondary/primary activity with a capacitive probe. The last one can sometimes be done by placing a pickup in proximity to the coil but, if that isn't fruitful, it may be necessary to install coil extension leads between the plugs and the coils.
THE PicoScope Automotive Authority
In North America