Nearly a tie: Indonesia and Saudi Arabia differ by barely 3%% in area — about 1,872,242 km² km² against 1,925,871 km² km².
Both sit in Asia, so this is a same-region comparison: the new Equal Earth map draws both with the same honest geometry, and the real gap is exactly the 1× you see above.
The old Mercator map treated both about equally (1× vs 1.2× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Indonesia fits 1× into Saudi Arabia.