Open the Google Doc
Place the cursor where you want the PDF content
Click Insert
Select Image or Drawing if you want to add a PDF page as an image after converting it
Upload the PDF to Google Drive
Open the PDF in Google Drive
Use Google Docs to open the PDF if you want to convert it into editable text
Copy the converted content from the new Google Doc
Paste it into your original Google Doc
Insert a link to the PDF in Google Drive if you want to reference the file directly
Use Insert then Link to add the PDF link in the document
Add the PDF as an attachment in Google Drive and share the file if needed