That's bad idea to ship via courier for Shopify store unless the product price are very high as the courier shipping service is extremely expensive during COVID19. If you dropship from South Africa to worldwide countries, you'd better try post service and find some local shipping agent with international post service.
ShipAnt.com - Chinese dropshipping agent - reliable sourcing agent
Based on your query I would like to recommend Ship, Rate And Track for FedEx by PluginHive. This app allows you to get accurate real-time shipping rates. Moreover, the best part is that you will get free access to this app for 2 years. Let me know if you have any query.