HI Mr Thicc
Omar is correct about sculpted models and/or models that were made my AI. (They will be super dense meshes with 40 bazillion vertices)
But if you import a model that was made with CAD, or it has been converted to STL for the purposes of uploading to a site like MakerWorld or Printables etc.
Then it will always be triangulated.
You can press Alt+J in edit mode to convert triangles to quads.
However this will only work on the more logical topology. It’s not going to work on everything. (long skinny triangles that you get in fonts->geometry won’t be fixed, and any surface where the STL created fan-like faces will still require cleanup)
Hope that helps.
