Isshiki explains how he can feed either Boruto or Kawaki to the ten tails and grow a chakra fruit by himself and eat it to become a real Ohtsutsuki. This is where we stop. These are only early spoilers, so we recommend watching Boruto 219 English subbed episode when it airs online.
Kawaki Arc. In episode 190, Kawaki was sent to the Scientific Ninja Lab for a checkup and to cure him after he collapsed because of the fight he had against Garo. After Kawaki woke up, Sumire, Boruto and Mitsuki were sent to feed Kawaki, but Kawaki aggressively causing everything to fall and hurt Sumire.