Go read some documentation. Here are some suggestions:

Gain fluency for managing GPG keys using dirmngr
See dirmngr(8)

Linux Kernel Administrator and User's guide
https://www.kernel.org/doc/html/next/admin-guide/index.html

Guide to UEFI Booting
http://www.rodsbooks.com/efi-bootloaders/index.html

Systemd
http://0pointer.de/blog/projects/systemd.html

D-Bus
https://www.freedesktop.org/wiki/IntroductionToDBus/

Linux Accounting & Audit System 
https://www.kernel.org/doc/html/v5.8/accounting/
https://documentation.suse.com/sles/12-SP4/html/SLES-all/cha-audit-comp.html

Selinux
https://github.com/SELinuxProject/selinux-notebook/blob/main/src/toc.md

Fluentd: pen-source data collector for unified logging
https://docs.fluentd.org/

ntftables
https://wiki.nftables.org/wiki-nftables/index.php/Quick_reference-nftables_in_10_minutes#Tables
https://wiki.nftables.org/wiki-nftables/index.php/Main_Page

Firewalld
https://firewalld.org/documentation/

Linux Memory Management Documentation
https://www.kernel.org/doc/html/v5.8/vm/index.html

LEDs
https://www.kernel.org/doc/html/v5.8/leds/

RHEL guides
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/

RHEL Networking Guide
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/

Other
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https://selects.acm.org/selections/getting-started-with-swe-best-practices
"These skills will allow you to increase your impact from developing
small/standalone projects to an industrial scale."

60 Minute Lecture: How To Speak by Patrick Winston
https://www.youtube.com/watch?v=Unzc731iCUY