Both the Gear Packs and season pass of past Gears of War games won't be appearing in Gears of War 5. Instead, the focus is on the Tour of Duty, a battle pass-esque system for completing challenges across seasons of play.
In a blog post, The Coalition breaks down what is and isn't in this pass system. All DLC maps will be free for matchmaking and private play, so the stuff you're buying is going to be customization options. The Tour of Duty is a free set of paths towards content like skins, with each clearly set out so you know what you need to do to progress towards them. It's also seasonal, so new items will rotate in and out, and the blog specifically says there won't be any "premium" pay-only content.
You'll also get Supply Drops for every minute played in multiplayer, which will go towards random item drops from another pool of content. Any duplicates get turned into Scrap, which you can spend to buy other Supply Pool items you want, and this content also cannot be purchased with real-world money.
So what can you actually buy with money? There will be exclusive content purchased with a real-money currency called Iron, which you can also earn through each Tour of Duty. These are direct purchases, so no random boxes, and none of these items will provide a "competitive advantage." You can also buy a Boost, which will give you double XP and Supply Drop progress.
The message is fairly clear: no gameplay-critical stuff is purchasable, and while there are pseudo-loot boxes, they won't be directly purchasable with real money. (Boosts can be construed as spending money to get more drops, but that's a few steps removed.) It seems almost a direct response to the regulations set forward by various loot box bills. It's a good thing, and makes me more eager to play Gears 5, knowing that if I see a cool skin I can just buy it rather than rolling the slots for it. But it's very interesting seeing the clear, direct messaging ahead of game releases, conveying how non-loot-boxy their games are. We'll see more on September 10, when Gears 5 hits the Xbox One and PC.