How exactly are you doing this? Can you describe the process, so that we see, what you are doing wrong?

At a scale of 20 km the resolution is shwon in the figure. I start by drowing a rectangle to select my zone, then I use Javascript to download b04 for example ( return [B04]; ).

the resolution in arcgis in shown in the figure (39x36). ![screan shot|690x388](upload://jF2eJULdO8GT0GcpwOlbSW7FC9j.jpeg

EO Browser supports download of about 3.500 x 3.500 px. So you need to zoom in and download there. The download tool displays the estimated resolution, e.g. 160m in this case:

I suggest you try Sentinel Hub OGC services to use the data in ArcGIS:

Standard Services

Get Satellite Data in Your On-line or Desktop GIS Application - Use our WMS/WMTS/WCS service to avoid the complexities of Sentinel satellite data.

Thank you for you response, but i need to cover a large area in limited time. If there is a solution to have the same dimension of the sentinel L2A downloaded from copenicus hub with the same resolution that could be genial.

No, this is not possible with EO Browser. I suggest you download the data from copernicus hub then.