@SMukherjee9 Glad I helped answer the question.
In order to retrieve all properties, you will need to include them all within that array.
In order to format the request quickly you can just use this endpoint (it’s the same one you mentioned but a newer version)
url = "https://api.hubapi.com/crm/v3/properties/contacts"
This will give you a full list of all the properties in the system (an internal list, not the values on the specific record.) Then you can use something like JSON to CSV (or create a script to just get the “name” value. (something like results.name[0] for each result in the array.) This will give you a full list of all the properties internal name.
Then you can add those all to the initial request, and you’ll get a list of all the properties for that specific contact.
Also, note that the response you sent indicates Invalid Authentication - this means your access token is invalid. You should be able to get it within your private app.
Feel free to DM me if you need any help.