Should I lift weights as well?

If you enjoy lifting, keep lifting. Strength helps. It is just not the priority.

The order is skill first, conditioning second, weights third. A strong person with no technique loses to a technical person nearly every time, in grappling especially, and hours under a barbell are hours you did not spend drilling.

Two or three simple sessions a week is plenty alongside fight training. Compound movements, moderate volume, nothing that leaves you unable to move the next day. Grip, legs, back and midsection do the most for you here. What you do not need is a bodybuilding split that wrecks you before we train, or a new max the week of a match.

Put the lifting on different days from hard mat work, or after it rather than before. Turning up to spar on dead legs is how people get hurt and learn nothing while they do it.

It is worth being clear about what strength actually buys you, because people over-invest here. It buys you a margin when technique fails, and it buys you less fatigue late in a round. It does not buy you position, timing or a pass. See do you need to be strong to do jiu-jitsu.

Inside a camp the whole thing inverts. The lifting shrinks as the date gets closer and the mat work grows, because you cannot build strength and sharpen skill in the same eight weeks without something breaking. Fight week it is maintenance or nothing. See how long a fight camp runs.

For teenagers already playing a school sport, keep it simple, keep it supervised, and do not stack it on a hard practice week. See training for a school sport.

Tell me everything else that is in your week. Running, surfing, the other gym, work that keeps you on your feet all day. I build the hour around your actual week, not an ideal one. See recovering between sessions.