You can update this icon by modifying the underlying view rule for the Explore Data landing page.
Note: Since this requires overriding an out-of-the-box (OOTB) rule, you will need to manually retrofit and test this configuration during future platform upgrades to ensure you don’t miss out on base updates.
I dont think there is a direct option other than overriding the icon which @VVNagaSaiN has mentioned.
Alrernatively, If your purpose is only to differentiate Home and Explore Data visually, one practical option is create a custom landing page for reports, add that page to the portal navigation with a distinct icon and remove the default Explore Data item if your business users are meant to use the custom reports entry instead
As a best practice, avoid direct customization of the OOTB Constellation portal unless configuration does not meet the requirement. If the standard configuration is insufficient, then evaluate a supported extension approach such as a custom portal page rather than modifying the default portal behavior itself.