[Tactics]

By eating.

Yuji likely eat the rest of Death Painting, considering all the hints around him and Choso.
A narrative exploit if its true since Death Painting never really explained past they're able to use Blood Manipulation to certain degree.

Yuta though. We saw that he got Charles CT and Sukuna CT.
Ryu speculated Rika need to eat body parts of sorcerer to add the CT into Yuta arsenal because he saw Rika ate Uro;
Not difficult to expect Charles agreed to the deal thanks to Yuta RCT but Sukuna's, did Yuta find Sukuna's last finger?

Yuta's UBW surprisingly a tough deal if you think about it.
More copied CT = more randomized sword effects. So he better not copy everything just because he can.