Go to https://decoder.link/converter
Go to PEM to PKCS#12, upload new certificate, existing key and bundle from new certificate > enter password to convert and download the PFX key
How To : Convert certificate (PEM) to PFX (PKCS#12)
Go to https://decoder.link/converter
Go to PEM to PKCS#12, upload new certificate, existing key and bundle from new certificate > enter password to convert and download the PFX key