Cross Bombs are a new upgrade in Metroid Dread. This upgrade functions similar to a Bomberman bomb, creating a chain reaction both vertically and horizontally, destroying all bomb blocks in its cross-shaped path. This also can propel Samus many spaces forward, carrying her over blocks that break immediately.
To obtain this useful upgrade, you will need to head to Ghavoran and contend with Golzuna, located here:
To reach Golzuna, you will need to have obtained the Space Jump, located in Ferenia, and the Gravity Suit, located in Burenia. Cross Bombs are one of the last upgrades Samus will acquire in the game, with only the Wave Beam and Power Bomb remaining, so it may not be a bad idea to explore and obtain some Missile and Energy tank upgrades before proceeding.
This upgrade is required to obtain many Missile Tank+ and Power Bomb expansions, as the developers tend to hide these behind quick-break blocks and Bomb blocks. To activate Cross Bombs, hold R and press Y. Much like regular Bombs, Cross Bombs have an infinite stock, so use them to your heart’s content. Once you unlock Power Bombs, you will need to activate Cross Bombs quickly before the charge for a Power Bomb is complete.