Consistent capitalisation in headings and sub-headings makes your article look tidy and professional.
Understanding what to capitalize in a title is important to make sure that your titles and headlines look correct.
There are two methods:
Option 1: Use https://capitalizemytitle.com/
You simply copy/paste your sub-heading into the field and CapitalizeMyTitle.com will convert it into an APA style heading. Always use this, if in doubt.

Option 2: Follow the client’s lead.
Look at existing blog articles on the client website. Follow the same capitalisation pattern that they use for their headings, brand and product names.