@saleem72 Have a read of https://wiki.openstreetmap.org/wiki/OSM_on_Paper - ignore the “on paper” part of the title, that page explains how to generate large maps in various styles, which once created you can usually download as an image (if only via browser screenshot).
On Android you’ve got a choice - you can access websites that display on the phone, and you can download apps that can display online or offline maps. There’s more information at https://wiki.openstreetmap.org/wiki/Android . Unfortunately that page is a bit of a mess, but if you say what you are trying to do people will be able to help. The two most widely known OSM-based navigation apps on Android are probably OsmAnd and MAPS.ME - see https://wiki.openstreetmap.org/wiki/Android#Navigation , but many other people incorporate OSM data into their own data and their own maps.