Returning an updated array after for loop has finished

Question

I have an async function that calls one API end point to pull the sales orders for the day, retrieves the sales orders info and pushes each sales order object to an array (salesOrders); then I for loop through each sales order in the array, call another API endpoint to retrieve the line items for each sales order, and then appends each line item to the lineItem array inside of said sales order object.

I'm posting the last half of the function since the first half of the function where it retrieves the sales orders and formats them works.

Clearly my function is returning my salesOrders array before the forEach loop has had a chance to finish retrieiving, formatting, and appending the line items to each sales order object's lineItem array. How do I return the salesOrders array where each sales order object has an updated lineItems array?

//SEARCH THROUGH EACH SALES ORDER TO FIND LINE ITEMS
salesOrders.forEach(order => {

    let filterPrefix = "?filter=SalesOrderRecordID eq ";
    let formattedURL = baseURL + salesOrderLine + filterPrefix + order.RecordID;
    formattedURL.toString(); 

    axios.get(formattedURL, options).then(res => {

                let data = res.data.value

                data.forEach(item =>{

                    //CREATE A LINE ITEM WITH MORE INFO THAN NEEDED FOR KATANA, MAY NEED TO CREATE A NEW PRODUCT IF ONE NOT FOUND
                    let lineItem = {
                        customer_id: order.KatanaCustomerID, //katana customer id
                        recordID: item.Item_RecordID, //record number in method, not necessary in Katana
                        SalesOrderRecordID: order.RecordID, //actual sales order record id in method, not necessary in Katana 
                        order_no: order.RefNumber, //sales order number
                        variant_id: '', //variant id --> the ID in Katana, blank for now
                        name: item.Desc, //item description in method will be item name in katana
                        quantity: item.Quantity,
                        price_per_unit: item.Rate, //price per unit
                        category_name: item.ItemType, //Category in katana
                           //IF we have to create a new product, variants object is required for Katana
                        is_producible: true,
                        is_purchasible: true, 
                        variants: {
                                        sku: item.Item, //the SKU in method, it could be a product OR material in Katana
                                        purchase_price: 0,
                                        sales_price: item.Rate,
                                        config_attributes: {
                                            config_name: 'standard',
                                            config_value: 'default'
                                        } 

                                    }
                
                    }
                    //console.log(lineItem)
                    order.LineItems.push(lineItem)
             
                })
            })
            .then(result => {

                console.log(salesOrders) // stockoverflow friends -- the salesOrder object in this step includes all of the properly formatted line items in the lineItems array
                return salesOrders; //obviously pointless, not returning anything to any variable
                 
            })
            .catch(err => {
                console.log(err)
            })


    
}) 
console.log(salesOrders) //the line items array is empty, obviously returning salesOrders before the for loop has had a chance to populate each line item array
return salesOrders  }