Im trying to add projection 'EPSG:6875' to my openlayers but I don´t know how the parameters work. Can someone explain me how could I do it. I have this code as example:

proj4.defs('EPSG:21781',
  '+proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 +k_0=1 ' +
  '+x_0=600000 +y_0=200000 +ellps=bessel ' +
  '+towgs84=660.077,13.551,369.344,2.484,1.783,2.939,5.66 +units=m +no_defs');
register(proj4);
const swissProjection = getProjection('EPSG:21781');

I would like to do the same for 'EPSG:6875'