Offline map / tiles downloading

I was asked to create an offline map using OpenStreetMap.
So I wanted to know what apps or website that I could use to download some tiles ? (because I can’t do it from the servers, as i don’t know how many we would need in the future)

Or is there other way to create achieve my goal ?

Some options for an easy start depending on the kind of tiles you need:

raster tiles:

vector tiles:

or - depending on what you need - the rather time and cpu/ram/disks consuming way: create the tiles yourself, e.g. by using Tilemaker for vector tiles or by following a guide at Serving Tiles – Switch2OSM for raster tiles.