Missing fonts for which others have been substituted will appear at the top of the Type > Font menu in a section marked Missing Fonts. When this happens, you can select the text and apply any other available font. If there are any missing fonts that do not have suitable fonts in Adobe Fonts, they will be substituted with default fonts. InDesign auto-activates missing fonts in your document with an available Adobe Font.
If you select text that uses a missing font, the Character panel or Control panel indicates that this font is missing by displaying it in brackets in the font style pop‑up menu.