Closer than most people guess: Democratic Republic of the Congo (2,334,703 km² km²) is only about 16%% larger than Kazakhstan (2,712,747 km² km²).
Democratic Republic of the Congo sits in Africa, Kazakhstan in Asia. On the old Mercator map the latitude gap distorted how large each felt beside the other; at true size the answer is simply 1.2×.
The old map muddied it further: Mercator inflates Democratic Republic of the Congo about 1× and Kazakhstan about 2.3×, so on a Mercator-style map this pair appears 2.6× apart instead of the true 1.2×.
Democratic Republic of the Congo fits 1× into Kazakhstan.