Your military defense counsel will discuss with you the terms and requirements of a pretrial agreement, should you decide it is in your best interest to get “a deal.”
However, once that deal is signed, the judge accepts it, and it is now on appeal, it is hard to get the appellate court to reduce the sentence that is actually adjudged so long as it is within the specified limits of the deal and does not contain any clause that violates public policy. United States v. Spencer from the Navy-Marine Corps Court of Criminal Appeals is one example of how the appeals court looks at the sentence appropriateness where there is a pretrial agreement.
The Navy–Marine Corps Court of Criminal Appeals (NMCCA) reviewed LCpl Spencer’s sentence de novo under the pre‑2023 version of Article 66(d)(1), UCMJ. That statute authorizes the service courts to approve only so much of the sentence as they find “correct in law and fact” and, on the whole record, “should be approved.” Congress removed this text when it overhauled military sentencing in the Fiscal Year 2022 NDAA, but the new regime applies only to offenses occurring on or after 27 January 2023, so the legacy standard controlled here.