We have some ideas, of course. The rough idea is: surround the reactor with a lithium blanket. This gets bombarded with neutrons, breeding fuel and heating the lithium, which transfers its heat to coolant to spin turbines. The devil is in all the engineering details, like: how do we make alloys to deal with neutron bombardment/hydrogen embrittlement, what's the optimal geometry to capture flux while being serviceable, etc.

Much of that work can and is researched in parallel, but there will be inevitable integration hell that has a burning fusion reactor core as a prerequisite.