There is 1p, 3p ,5p attribute for elsarticle. How could I determine which model should be used? Could you tell me where can I find out the model of all elsevier journals?
According to the documentation, the options to use for article submission are
review. Hence, you do not need to know the journal's model to submit. If your article is accepted for publication, the journal should send you instructions on final formatting. If they don't, then you can just ask your copy editor which option you should use. Even if you knew the relevant model, the journal will not want that model used for initial submission and review. (And may well send it straight back to you if you submit in that format.)
The 1, 3 and 5 refer to the paper size: 165x240mm, 192x262mm and 210x280mm respectively. Just download a PDF or get a hard copy from the library for your journal and check its dimensions.
As cfr points out, you're not expected to submit your manuscript in the final print layout of the journal. It's usually a lot easier for editors and reviewers if you use one column (for online readability) and your standard paper size (for printing).