Buy two 40 amp regular automotive relays. Buy a spool of 10 gauge wire. Two fuse holders, wire terminals and fuses.
Currently it is likely that power to your head lights goes through your light switch. You will use these wires to close/open the relays-- one for low beams, one for high beams. Locate the relays/cut the high/low wires in any convenient location.
Supply power to the relay from any large gauge positive wire in the area-- plenty in either in the under dash or nose area of DP's or obliviously in front engine vehicles. Connect the fuse for each to that connection or even positive terminal of the battery if front engine. Then with the 10 gauge wire to the relays.
Then if wires to the lights are currently small gauge, replace wires from the relays to the lights and lights to ground.
It is amazing how much brighter a headlight is with 13.5+ VDC to it vs 11.8-12.2 that is so common with those long small gauge wire and drop in the head light switch.