This format change is for Importing Browser.

openssl pkcs12 -export -in example.crt -inkey example.key -certfile chain.crt   -out example.com.pfx

or

openssl pkcs12 -export -in example.crt -inkey example.key   -out example.com.p12

or

openssl pkcs12 -export -in "input.pem"  -out "output.p12"

# openssl pkcs12 -in sample.pfx -clcerts -nokeys -out xxxxx.crt
# openssl pkcs12 -in sample.pfx -nocerts -nodes -out xxxxx.key
# openssl pkcs12 -in sample.pfx -cacerts -nokeys -out xxxxx.ca-bundle

openssl pkcs12 -in "input.p12" -nodes -out "output.pem"

openssl x509 -in "input.pem" -inform PEM -out "output.der" -outform DER

openssl x509 -in "input.der" -inform DER -out "output.pem" -outform PEM

OpenSSL - How to use OpenSSL from the outside