Clearing the cache partition will not mess up you phone. It is only deleting archived data and corrupt files. By doing this it frees up storage and processing because there is less for the phone to deal with.
Turn off the device.
Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
When the Android logo displays, release all three keys.
An ‘Installing system update’ message will show for 30 – 60 seconds before the Android system recovery menu options appear.
Press the Volume down key several times to highlight wipe cache partition.
Press Power key to select.
Press the Volume down key to highlight yes, them and press the Power key to select.
When the wipe cache partition is complete, Reboot system now is highlighted.
Press the Power key to restart the device.
Your phone will take a little time booting up after the cache partition is wiped off of its contents as it will rebuild or recreate those caches.