For S0 Max requests (concurrent workers) is 60 as explained here. To support 1,000 or more you need S7. S7 has a limit of 1,600 requests.
S7 cost you $1.6130/hour on EastUS, please use this URL to calculate based on the Azure region of your preference.
Some more information for you about S7, it allows a minimum of 6 cores or 12 cores depending on hardware generation, 19,200 maximum number of sessions, maximum worker threads 2,675.