“Orders” can have more than one meaning. There are, e.g., general orders, unit orders, operations orders, fragmentary orders, and warning orders.
For example, if one states, “I have orders,” normally that means one has been transferred to a new assignment and the “orders” are what spells out to where, in what timeframe and the various administrative details of the move. See some 58 pages of samples starting on page 21 of this document:
Headquarters can publish general orders, each numbered sequentially by year which list changes in personnel and units in a paragraph form, thusly:
All that aside, I am presuming you are referring to what long ago were called "field orders", now, the Operations Order, or OpOrd. The OpOrd follows a basic format/template which guides the order writer to make sure nothing important is left out. It incorporates the commander’s intent and 5 specific paragraphs which must be addressed: Situation, Mission, Execution, Sustainment, and Command & Control. See https://en.wikipedia.org/wiki/Operations_order
This monograph provides some historic background to the development of standard operations order formats in US service, “The Five Paragraph Field Order: Can A Better Format be found to Transmit Combat Information to Small Tactical Units” https://apps.dtic.mil/dtic/tr/fulltext/u2/a210966.pdf (Smith). While the simple Wiki search for the 5 paragraph operations order credits Frederick Edwin Garman for its development in the late 1950s, clearly there was an evolutionary process going back to at least 1897 for the US Army and which some sources contend was rooted in the planning processes of the German Imperial General Staff.
For some further discussion of the relevance of the five paragraph OpOrd, also see this “Analysis of the Tactical Orders Process” https://apps.dtic.mil/dtic/tr/fulltext/u2/a227390.pdf (Antal) and “The Standard Operations Order Format: Is Its Current Farm and Content Sufficient for Command and Control?” https://apps.dtic.mil/dtic/tr/fulltext/u2/a191781.pdf (Filberti).
Has it changed since 1897, or even 1958? Certainly, but since the late 1950’s the OpOrd 5 paragraph format as used in US service has remained relatively unchanged except to add relevant additional information and updated terminology. For example, “Sustainment” is one of those updates, way back when I was known to produce an occasional OpOrd, this paragraph was entitled “Service and Support”.
Normally the lowest level which might produce a OpOrd is usually a battalion HQ. The battalion’s companies would receive the OpOrd, the company’s platoons and, yes, even squads, would be tasked with fragmentary orders (FragO) drawn from the information contained in the OpOrd and might be augmented (note “augmented” not “changed”) by information in the immediate location. A FragO to a squad or platoon might lead to the development of a patrol order which would spell out the plan or the basic unit to accomplish the tasks set forth in the OpOrd. Information flows downhill in smaller and smaller packages . . . but all follows the template as set in the OpOrd. The Marine Corps Basic School has a nice little training package for the PatOrd: https://www.trngcmd.marines.mil/Portals/207/Site%20Images/TBS/B2H0375%20Patrol%20Order%20and%20Overlay%20Workshop.pdf