This can still be done in the current game. I can offer someone 100k cash in exchange for peace, lets say 5 days of peace. The only thing that cannot be enforced is whether I actually don't attack you for 5 days.
In real life should two nations agree to something like this, there is nothing mechanically preventing one to go and attack the other 3 days later. Yes the world would likely frown upon this action, but that can occur in game. If players sign a peace like this. I would encourage you to post it in the WH (world herald / newspaper). So that should someone betray the agreement the world can see they have done so.
But should a player attack after the 3 days that is up to them. Forcing players to not be able to act like one does in real life I wouldn't support. This is a game of diplomacy, blindly trusting someone won't betray their word is foolish imo.
When Hitler said he would stop at the Sudetenland and then ate up the rest of Czechoslovakia, there was nothing preventing him from doing that. Sure it was an ass move, but like in-game, players can do that.