APA papers should have a one inch margin on all four sides.
Page numbers live in the top right corner of the page, even on the title page.
Optional, unless required by an instructor. If needed, it would share a header space with the page number on every page, and be left-justified.
Double line spacing is used throughout. Do not add extra spaces between paragraphs or sections.
Other than centered headings, text is left-justified, which means the right margin will be ragged instead of uniform.
Do not manually or auto-hyphenate words to smooth out the right margin. (As an added warning, hyphenating a URL in the reference list will change it to something else.)
In the body of the paper, the first line of a paragraph starts with a 0.5 inch indent.
In contrast, references use a hanging indent, meaning that the first line of each citation will touch the margin and following lines will be indented 0.5 inches. This format makes it easier to find sources in the reference list.
Unless your instructor specifies otherwise, choose a legible, accessible font to use consistently through the entire paper.
APA 7 recommends: