The phrase "a vast extension" is correct and usable in written English.
It can be used to describe a large area or a significant increase in something, such as land, time, or scope.
Example: "The project involves a vast extension of the existing park, providing more space for recreational activities."
Alternatives: "a wide expanse" or "a large area".
So including them in the Animal Protection Act is a vast extension of the law's reach.
The new proposal involves a vast extension of the area of control.
In the Grand Mosque itself, a group of 500-year-old stone columns and vaults have now been demolished to make room for a vast extension.
There needs to be a vast extension of the way public guarantees and private insurance are available to relieve some of the risk in lending to support innovation.
As indicated in the map, the Sierra de los Frailes glaciation would have expanded over a vast extension, between the Rio Gallegos valley and Central Tierra del Fuego.
The PSA wants to grab its own share of the new Asian trade, and to that end is building a vast extension on reclaimed land.
However, following the introduction of a mixed economy and the vast extension of state welfare services under the Labour government of Clement Attlee after 1945, the Conservatives reversed very few of their predecessors' innovations when they returned to power in 1951.
The mountain as a meeting place of heaven and earth, gods and men, and master and disciple (as already in Zhuangzi), takes on a vast downward extension.
With its vast extension about to open, Tate Modern has a lot of space to waste.
The vast majority of Jews brought to Auschwitz never experienced the camp as prisoners; more than eight hundred thousand of them were gassed upon arrival, in the vast extension of the original camp known as Birkenau.
"The big (farmers) have vast extensions of land and have the means to recover all the areas of permanent preservation," Brazilian environment minister Izabella Teixeira said.
