Variables values

I have configured var.tf with variable as below
variable “stack_env” {
type = map(string)
default = {
full_name = “daily”,
short_name = “daily”,
upper_case = “DAILY”
}
}

it has default values and its working but how can I override the default value and what are the option to override? using main.tf? or var file?
Tnx