Override default value in a map

Terraform
1

Is there any way to override the default value that is set as locals in the module and in the invocation part?

In module default value looks like this:
module.tf

locals {

  default = {
    "defaul_instance_1" = {
      instance_id        = "test_1"
      instance_type     = "t2.medium"
      ami                = "ami-1234567"
      instance_config        = {
        ebs = {
          "xvdb" = 20
        }
     },
    "defaul_instance_2" = {
      instance_id        = "test_2"
      instance_type     = "t2.small"
      ami                = "ami-1234567"
      instance_config        = {
        ebs = {
          "xvdb" = 30
        }
     },
...
  }

variable "instance" {
  type = map(string)
}

and in module calling part would like to override any value depending on the case, for example:

module "ec2" {
  source = "./module.tf"

 instance = local.instance
}

locals {

  default = {
    "instance" = {
      instance_type     = "m5.xlarge"
      instance_config        = {
        ebs = {
          "xvdb" = 100
        }
     }
  }

Or is there any better way to handle this

Thank you