@Engineer101
A good place to start are the datasheet for the Cisco Secure Firewalls (9300 and 4100), determine your throughput, number interfaces etc and identify the model that fits your needs.
https://www.cisco.com/c/en/us/products/collateral/security/firepower-9000-series/datasheet-c78-742471.html
https://www.cisco.com/c/en/us/products/collateral/security/firepower-4100-series/datasheet-c78-742474.html
The NGFW performance estimator tool is probably more useful, you can select which features you plan on using Firewall, IPSec, NAT, Threat, Malware, URL the estimated throughput and will then provide you a list of recommended hardware....but this available only to Cisco and Cisco Partners.
