Q: What does 'Decision in Process' mean for a Taylor and Francis journal?

Ideally, once a paper is assigned to an editor, this person conducts an initial screening of the manuscript to decide whether the paper will be sent for peer review or desk rejected. If the paper clears the initial editorial screening, the status changes to "Assigning reviewers" or "Reviewers invited." On the other hand, if the paper is likely to be desk-rejected, the status changes to "Decision in process." Thus a direct change from "Editor Assigned to "Decision in process" usually indicates a desk rejection. However, your case is a little unusual.

Generally, it takes a few days to assign an editor, as the manuscript has to go through an admin check first. However, in your case, the paper was assigned to an editor immediately. Moreover, it also seems that the editor completed the initial screening of your paper in a day, which again is rather unusual. 

Therefore, it is difficult to predict the outcome in this case. The next status change will make things clearer.

Related reading:

• Does a direct 'Decision in Process' status indicate rejection?
• My manuscript's status changed from "With editor" directly to "Decision in process" and it remains so for over a month. Why?