Large City in Region
trade_goods_size_modifier = 0.1
local_development_cost_modifier = -0.05

Largest City in Subcontinent
prestige = 0.1
trade_goods_size_modifier = 0.15
local_development_cost_modifier = -0.10

Largest City in Continent
prestige = 0.2
trade_goods_size_modifier = 0.2
local_development_cost_modifier = -0.10

Largest City in the World
prestige = 0.3
trade_goods_size_modifier = 0.3
local_development_cost_modifier = -0.10

Every year, Large City and Largest City will have a chance to increase their development. Every 0.01 local development cost modifier lower than 0.20 gives 1% development increase chance.

By default the minimum chance is 5%, but the minimum chance can be configured.