What would be the hypothetical conditions for an Earth-like planet to have tundra or taiga as dominant biomes?
Taiga is the largest non-oceanic biome on Earth. But if you want it to be even more prevalent, take your pick:
A thinner atmosphere unable to retain as much heat.
An orbit closer to the outer edge of the star's habitable zone.
Smaller oceans; like the thinner atmosphere it would mean less heat is retained and distributed around the globe.
Assuming you are talking about non-oceanic biomes that is fairly simple. Just remove all the parts with wrong biome.
Basically you'd only have continents in 45° to 65° latitude in both northern and southern hemispheres. Make them old without large mountainous areas to mess things up and leave gaps to get oceanic heat transfer between the huge tropical ocean and the polar oceans.
The planet would probably need to be farther away from its star to compensate for large tropical ocean reducing albedo and for the continents being bit farther from the poles than taiga is on our world.
I suggest that the axial tilt should be zero. That way the long polar nights can be avoided and there is a greater area for forest.
The distance from the sun should probably be moved out a little to cool the planet down.
The oceans should be arranged more in the tropics where the rain forests and deserts currently are and extra land should be provided in the northern and southern higher latitudes.
I've seen a lot of suggestions about orbiting the planet further away from its star and reducing the axial tilt. I'd like to point out that you also have to keep an eye out for dead horse zones (https://en.wikipedia.org/wiki/Horse_latitudes) and other natural phenomena that will cause barren areas, or relatively warm areas.
Also, note that like on earth, people will prefer to settle in places that are hospitable. If you have any point where the temperature is warmer, or the weather conditions are good, people will want to settle there. Tundras are harsh places, and there is a good reason why they are among the least settled parts of our world.