There are always exceptions. For every one exception there are a hundred examples of the opposite.
Easier said than proved.
We already know #1 in both categories, most safe and most dangerous.
Here's 2 and 3 in both categories:
#2 safest city in the world: Singapore, Singapore... population over 5.7 million
#2 most dangerous city in the world: San Pedro Sula, Honduras... population over 800,000
#3 safest city in the world: Osaka, Japan ...population over 2.691 million
#3 most dangerous city in the world: San Salvador, El Salvador...population over 238,244
Do you remember when a 19 year old American man was arrested for vandalism, caned, jailed for 12 weeks and fined $2,300?
That still makes my point. All other things being equal, the bigger the population, the higher the crime. But there are more factors like policing, demographics, poverty....