There is a growing trend in research articles' authorship varying from five in number to anywhere around 15 which I have noticed. How are these articles cited in-text (as the general rule was to cite all authors the first time and then use et al. and in the references section?
Each journal may have its own rules for such cases. If not, I would cite as "First Author et al." in the text, and indicate several authors (at least three) + "et al." in the list of references.
By the way, there are papers with more than 5000 authors, see https://www.researchgate.net/post/Group_Authorship_is_there_a_minmum_and_maximum.
I would recommend using reference manager software such as Mendeley, Zotero, or Endnote. It is much easier than doing it manually. Then, you can choose the referencing style (as determined by the journal or publisher) and it automatically gets it done both in text and as a bibliography at the end.