China dwarfs Saudi Arabia: about 9,371,225 km² km² against 1,925,871 km² km². At true size China is about 4.9× larger — the whole of Saudi Arabia fits into China roughly 4 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 4.9× you see above.
The old map muddied it further: Mercator inflates China about 1.6× and Saudi Arabia about 1.2×, so on a Mercator-style map this pair appears 6.3× apart instead of the true 4.9×.
Saudi Arabia fits 4× into China.