no
Khan was born around 1162
He was married to his first wife around the age of 16 with which he had spent rest of his life with and regarded as his most loved. Around that time he has also launched one of his first attacks on a rival tribe because they kidnapped her during their wedding days.
By his early 20s he had established himself as a formidable warrior and leader.
By the age of 43 he had vanquished all rivals, including enemy tribes and even his former best friend. He established a nation similar in size to modern Mongolia and was also proclaimed Chinggis Khan.
At the age of 47 he had his first campaign outside of Mongolia - in china and went from there
When he was 57, he was taking over Turkmenistan,
Uzbekistan, Afghanistan and Iran.
He died in 1227 at the age of 65.
He DID NOT “start” after his 50s. He was a warrior ever since he was a child. Killing his own brother when he was 14. A son of a dead tribal leader who had reclaimed his right for power by being capable. Uniting his nation in his 30s and 40s and moved beyond borders once he has put his nation under his order. He was very accomplished his whole life and it took time to get there. Time, trials, failings and mastery. He won but also lost wars. Was even enslaved for time or dissappeared after a lost battle for years without people knowing what had occurred to him to this day only for him to reappear later. Point is… it took time. A lifetime you could say and lifetimes of his sons and grandsons who had later doubled the area of the Mongol Empire after his death.