There is a Little Square in front of the Three Pagodas in Dali and a golden phoenix in the middle. What does this golden phoenix mean?

That's not golden phoenix, that's Dapeng Golden Winged Bird. Mr. Jin Yong mentioned Dapeng Goldfinch in Eight Dragons. In Buddhist scriptures, it is one of the "Eight Dragons", and its Sanskrit name is Goruda. It was naked when it was born, and all the gods mistook it for fire and worshipped it. Legend has it that Yue Fei, a famous anti-gold star in the Southern Song Dynasty, was reincarnated as "Dapeng Golden Winged Bird". Gruda's wings have all kinds of solemn colors. When the wings are open, there are 336 Wan Li. It has a big tumor on its head, which is a wishful pearl; It cries in pain, and its food is dragons. It flies in the air, patrolling the dragons that should die in the sea. When it found dragons, it fanned the sea with its wings, caught them and swallowed them. It eats one dragon and 500 dragons every day. At the end of its life, the dragons vomited poison and couldn't eat any more, so it spread its beautiful wings and flew up and down seven times, reaching the top of the diamond wheel, ending its heroic life.