formatting – Inline Section Headers for Google Docs

I am attempting to follow the APA style guideline for section headers. Under their guidelines, there are 5 different styles of section headers. The first three levels are on their own line, but the last two are inline headers:
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Source: https://apastyle.apa.org/style-grammar-guidelines/paper-format/headings

In google docs, the only way to achieve this is to manually change all Level 4 and 5 headers. This prevents them from showing up in the “Document Outline”. An example of this can be seen when looking at the default “APA” template provided by google docs. Their default template shows how to properly format APA using the inline header style, but their level 4 and 5 headers do not show up in the Document outline (They also label their levels slightly differently than APA in their example):

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I want to know if anyone has a workaround for this. In “Microsoft Word” the solution is to use Style Separators, but I am interested in using Google Docs.

There does not appear to be a way to do this in “vanilla” google docs, so I was wondering if anyone knows of a way to modify this default behavior (maybe a google add on?)

Other places I have seen people having the same issue:
https://support.google.com/docs/thread/9845129/how-do-i-pull-up-apa-formatting-so-i-can-write-my-paper-in-google-docs?hl=en
https://support.google.com/docs/thread/3402359/heading-is-being-applied-to-the-whole-line?hl=en
https://support.google.com/docs/thread/21333504/apa-headers-3-5-and-table-of-contents-issue?hl=en