On an iPhone 8 or iPhone 8 Plus: Press and quickly release the Volume Up button. Then press and quickly release the Volume Down button. Finally, press and hold the Side button until you see the recovery-mode screen.
On an iPhone 8 or iPhone 8 Plus: Press and quickly release the Volume Up button. Then press and quickly release the Volume Down button. Finally, press and hold the Side button until you see the recovery-mode screen.