It can't be done unless you choose to include some power resistors in your circuit for impedance matching. The problem with that would be some of your power will be lost in the form of heat across the resistors without the benefit of contributing any sound.

Also, the amplifier's damping factor will be compromised, so you may notice a loss in sound clarity. It's possible that you might not easily tell with subwoofers, depending on the enclosures they're mounted in, and whether they're isolated in a trunk vs being in the same airspace with you (hatchback, SUV, or pickup truck).

If you need further help, I’m available over the phone at https://www.6ya.com/expert/reginald_bec291de192ca44f