A useful book for students on using APA style is the Concise guide to APA style (7th ed.). This is aimed at undergraduate students and provides lots of useful information on formatting student papers. There are copies to borrow in the Library at:
https://library.lincoln.ac.uk/items/222508
Both the Library's APA referencing handbook and this APA referencing libguide focus on the referencing aspect of APA style which is outlined in the Publication manual of the American Psychological Association (7th ed.). As well as setting out the APA 7th referencing style, the APA's Publication manual covers all aspects of scholarly writing in APA style.
For guidance on how to format your academic work in APA style (including font size, spacing, headings, etc.), the first place to check is the information in the Module handbook and the Assessment briefing for a particular assessment. Both of which will be available on the module's Blackboard site. You can also check with your lecturer re the specific requirements for a particular assignment/assessment.
For general guidance on formatting a paper in APA style, there is lots of information available on the APA's website at:
https://apastyle.apa.org/style-grammar-guidelines/paper-format
This includes guidance on the following areas:
Fonts: https://apastyle.apa.org/style-grammar-guidelines/paper-format/font
Line spacing: https://apastyle.apa.org/style-grammar-guidelines/paper-format/line-spacing
Paragraph alignment and indentation: https://apastyle.apa.org/style-grammar-guidelines/paper-format/paragraph-format
Headings: https://apastyle.apa.org/style-grammar-guidelines/paper-format/headings
If in doubt about how to format an assessment, first check the module handbook and the assessment briefing and then, if still unsure, clarify this with the lecturer who has set the assignment. The above guidelines are those outlined by the APA for scholarly writing which may differ from those required for a particular assessment.
This recording of a webinar delivered by experts at APA Style for the Association of College & Research Libraries (ACRL) discusses how to format student papers - including font, line spacing, margins, page numbers, sections, and the reference list.
This APA tutorial helps writers who are new to APA Style learn the fundamentals. It includes guidelines for paper elements, format, and organization; academic writing style; grammar and usage; bias-free language; mechanics of style; tables and figures; in-text citations, paraphrasing, and quotations; and reference list format and order.
This free tutorial is available here