Secrets are all over Doom: Eternal, and a notable secret everyone will want to go after concerns the cute toys you can find in the game. The Hell on Earth level contains three of them hidden in the game, and finding them is a little out of the way while you run around the game’s mission.
You can find the first toy shortly after you begin the game on the Barge. You can find it behind a hidden wall you can break to your left when you enter the room with the piles of undead bodies stuffed into crates. The hidden wall is in the back, right before you find the block to gain access to the level. Punch through the wall, follow the path, and at the top is where you can find the toy.
The second toy is found near the start of the second area, right before you jump down the partially destroyed building where a massive mech is resting against a wall. Before you jump down, turn to the left and you should see part of a floor you can grab ahold of and go to the next level. Right around the corner, on the right, is the next toy.
The final toy in this level is roughly around the halfway mark of the mission. You can grab it after fighting a wave of demons near a store, the one with the blue sign that reads “Scott” above it. When you finish fighting them, go on top of the semi-truck outside of the shop. To your left, you should see a small lip of a cliff you can jump onto there, above where a sign reads “Shuz.” Go inside, and further inside to the left you should see a wall you can break down. Destroy it, hop down to the bottom, and the final toy will be there waiting for you.