No. Coffee strength and roast darkness are different concepts and are not necessarily related.
Coffee strength simply refers to how many coffee grinds are dissolved and extracted by your coffee maker and end up in your cup. Just like the alcohol level in a beer, coffee strength is expressed as a percentage of grinds to water in your cup.
A darker roast is more brittle and porous, which makes it easier for your coffee maker to dissolve and extract different flavors and aromas. But this does not necessarily add to coffee strength.
At Peak Flavor, we steer away from extra dark roasts because the extra roasting may cause burnt notes to dominate the more subtle sweetness of naturally sweet coffee beans.
Our Italian espresso roast is a little darker than medium roast. But we avoid roasting to second crack because it would cause bitterness in your coffee.