Hope you are doing well and sorry for the trouble. As described when you download and open the PDF it gives the view of 35% only.
Would you mind sharing the workflow/steps you are doing to open the PDF file? Are you opening it in a web browser or with Adobe Acrobat Reader DC application?
Is this a behaviour with a particular PDF file or with all the PDFs that you try to open? Please try with a different PDF file and check.
Are you referring to the zoom size of the document view? If yes, please try the following preference settings and see if that works for you. Go to Edit (Win) , Adobe Acrobat (Mac) > Preferences > Page Display > Under DEfault layout and zoom, select 100% zoom > click OK and check .