China dwarfs Indonesia: about 9,371,225 km² km² against 1,872,242 km² km². At true size China is about 5× larger — the whole of Indonesia fits into China roughly 5 times.
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 5× you see above.
The old map muddied it further: Mercator inflates China about 1.6× and Indonesia about 1×, so on a Mercator-style map this pair appears 7.8× apart instead of the true 5×.
Indonesia fits 5× into China.