Reacher's third season finished filming earlier this summer with leading man Alan Ritchson heading into hiatus with various projects including a revenge-motivated disco-rock movie, but Amazon knows a hit franchise when they feel one. The enormously successful Dad TV show also made an important break from Lee Child's books by moving slightly past Jack Reacher being the only character who will appear in each chapter.
That is to say, Frances Neagley will join Reacher in come capacity each season, beginning with the first season, based upon The Killing Floor, in which Maria Sten's character made a brief appearance although she does not appear in that book. This also helped the flow between seasons when Neagley sent up an ATM-fueled flare to call Reacher into action in the Bad Luck and Trouble-adapting second chapter of the Prime Video series. Amazon hasn't revealed how much of Neagley that we will see in the third season, which will be based upon the Persuader novel. We do know, however, that Reacher will fight somebody bigger than him, and we can speculate that Neagley will save Reacher's ass on the planning front.