Depends on the college. Level completed is probably what matters for most colleges, but some of the more selective colleges may prefer to see both a high level completed and a larger number of years of study.
If you earn a 5 on the AP Chinese test after taking Chinese 4, then taking the AP Chinese course afterward would look like grade-grubbing for an easy A. If you want to take the AP Chinese course, then wait until after that to take the AP Chinese test.
If you earn a 5 on the AP Chinese test after taking Chinese 4, but are concerned about some colleges wanting to see more years of high school study in foreign language despite having completed level 4, would you consider taking French, if your middle school French would place you in a higher level than French 1 (so that you can take two years of French reaching level 3 or higher)?
Which other AP course(s) would taking more foreign language courses displace?
A heritage speaker would be one who frequently used the language at home since early childhood.