Downloading a quite large square of land from openstreetmap

I’d like to try openmaptiles to play with style editing

Rather than using the predefined “regions” it has, I’d like to download a suqare of land that I’m specifically interested in

I tried but it seems my square is too large

How do I download such a large square ?

There are various options, the easiest might be but
you could also download a larger pre-defined region in .osm.pbf format
and then cut out the area of interest with a command line program like
osmium or osmosis.