I heard there are ways to predict how tall a baby will ultimately be, very soon after their birth. Is this true? Based on wrist/ankle size etc.?

The approximate rule. Here is a way to guess: add the heights (inches) of father and mother, divide in two, then add 2 inches for boy and subtract 2 inches for girl. For example: if dad = 71in, mom = 65in, then (71+65)/2=68; then 68+2 =70 for the boy and 68-2=66 for the girl. Just remember, this is an approximate. Life circumstances, nutritions, illness, long-term med use etc..Can affect it. Have fun and good luck.
Percentile. You can predict the grouth of a child by comparing him with other children in the grouth chart called percentile.If he is following the 90th in ht. Or wt. Then you know he is a tall and big kid . Ask your peds .