Add an Azure Cosmos DB NoSQL Data Plane Role Assignment using Azure PowerShell.

New-CosmosSqlRoleAssignment.ps1

$RoleDefinitions = @(
    @{
        Name = 'Cosmos DB Built-in Data Reader'
        Id   = '00000000-0000-0000-0000-000000000001'
    }
    @{
        Name = 'Cosmos DB Built-in Data Contributor'
        Id   = '00000000-0000-0000-0000-000000000002'
    }
)
$RoleDefinitionId  = $RoleDefinitions | Where-Object { $_.Name -like '*Contributor' } | Select-Object -ExpandProperty Id
$ResourceGroupName = ''
$AccountName       = ''

$PrincipalId = ''

$CosmosDBParams = @{
    AccountName       = $AccountName
    PrincipalId       = $PrincipalId
    ResourceGroupName = $ResourceGroupName
    RoleDefinitionId  = $RoleDefinitionId
    Scope             = '/'
}

New-AzCosmosDBSqlRoleAssignment @CosmosDBParams