Check out some guides related CPFP such as this one[1] if you must do so. You can also check the docs for Electrum to see how to do it[2]. While some images are no longer shown, you can still follow the text explanation. But as mentioned above, if the issue is not solved then you won't be able to do CPFP. Since you mentioned Electrum, do you use it to publish that transaction? Are you sure you don't enable RBF for that?

[1] https://bitcointalk.org/index.php?topic=5285192.0
[2] https://electrum.readthedocs.io/en/latest/faq.html