Richmond Royal park, London's biggest park is absolutely huge, 9.53 km².
Central park in new work is also huge at 3.41 km² and could also contain the area of the two smallest countries in the world. The Vatican city's area is about 0.5 km². Monaco has a surface area of about 2 km²
Central park, Vatican city state and Monaco City state would all fit inside Richmond park and there would be plenty of space left over.
Gibraltar island is not a country but it would also fit in the area of Richmond Park. The land area of Gibraltar is 6.8 km².
On top of everything, Richmond Park is considered to be a significant nature reserve filled with ancient trees and countless wild creatures that aren't found anywhere else in the area.
