Yes, it is possible. If you never exceed limits you probably have room to lower the power. If, on the other hand, they power jumps often, you are already at your limit. In the event that you add new appliances or increase the use, you will probably have to contact your electricity company to consider an increase in power.
Following Royal Decree-Law 15/2018 on urgent measures for the energy transition and consumer protection, it will be possible to contract the power in 0.1 kW sections, with the elimination of the normalized tranches that limited the contracting to these values.