The electric range of a plug-in hybrid vehicle depends on the size of its battery. In the case of CUPRA, the maximum electric range is 37 miles (CUPRA Formentor official WLTP test figures). The overall range when combined with the combustion engine is of course significantly higher.
Obviously, the range will depend various factors including driving styles, the topography, temperature and road conditions. The main advantage of a plug-in hybrid is that you always have the petrol engine as a reserve when between charges, so autonomy should not be a problem.
Learn about plug-in hybrid