Victory at the ballot box would make Paetongtarn Shinawatra Asia’s youngest-ever female leader. Whether she’s allowed to form a government is another question entirely.

The sun has just dipped from its blistering peak as Paetongtarn Shinawatra’s SUV rolls up at Wat Tha Luang, an ornate temple perched on the banks of central Thailand’s Nan River. Even before her desi…