Encryption method for crypt command in RHEL Linux 5.11

crypt command is used in our Linux shell scripts. Currently RHEL Linux server 5.11 is being used. The same crypt command is used for encryption and decryption. If anyone can give any inputs on how this encryption mechanism work it will be very helpful? After migration to AWS cloud server also will be upgraded to RHEL 8.9. How can we use the same crypt function in target server RHEL 8.9? Currently DES encryption algorithm is used in RHEL 5.11 which is not much secure. What encryption algorithm is preferred in RHEL 8.9?