Metroid Dread has many different areas to explore and many abilities to find as you do so. Some areas in Metroid Dread are inaccessible to Samus as her suit isn’t equipped to deal with different temperatures. One way around these areas is the Varia suit.
To unlock the Varia suit, you will need to head back to Artaria through the Red Teleporter in Cataris. From there, head down into the water and go left into the save room. Continue left and go through the Morph Ball tunnel. Continue upwards and to the right until you find a device that changes the thermal flow.
Related: How to get the Omega Cannon in Metroid Dread
Using this device starts a sequence in which you must run away from rising heat. Keep pressing onwards, blasting your way, or using the Morph Ball to continue. At the end of this sequence, you will find a Chozo Statue. Destroy the orb to unlock the Varia Suit.
With the Varia Suit upgrade, Samus can now withstand high-temperature rooms. This allows you to progress and also go back to previously inaccessible areas. You should note that the Varia Suit does not protect you from lava.
For more information on Metroid Dread, check out All Amiibo Functionality in Metroid Dread and How to unlock the Power Bomb in Metroid Dread on Pro Game Guides.