@browns149 said:

I’m not sure if this has been posted before. But there is a good article on Cleveland.com about how the NFL comes up with the schedule and who, and why the Browns play who they play

https://www.cleveland.com/browns/2021/02/why-the-browns-third-place-schedule-for-2021-is-one-of-the-nfls-toughest.html

First OP I've seen on the topic...

One caveat to the whole thing though is:   if the NFL  goes to the 17 game schedule, there will be some kind of adjustment/addition made.    The current formula is simple as ABCD

A. Play the teams in your division twice.

B.  Play all the teams in another division in your same conference on a round robin basis

C. Play all the teams in another division in the other conference on a round robin basis

D.  Play the teams that finish in the same place as you in the other divisions in your conference  not part of the round robin that year.

....But now they have to figure out how to add another team. to the mix.    Not sure how they plan to formulate that. 

Edit:  actually, after reading it more fully, the article addressed that:

MMQB’s Albert Breer reported that crossover rotation for the 17th game would match the AFC North against the NFC West in 2021. The third-place Browns would play the third-place Cardinals (8-8) in that scenario.

So, it seems every team would be adding a non-conference game