Let’s say your child wants to be an actor. One way to make this happen is to be a successful actor yourself - require your children to be cast in the film in return for you starring. This is how famous acting families pushed their kids forwards, including Nicholas Cage (Coppola) and Jeff Bridges.
More relevant for HN is rich people. So you are tech rich and your kid wants to act. Fund the movie on the condition your child acts in it. That is the way since movies began.
When they are younger they could pay for acting classes, acting camps and help them get into local productions.
Out of school they pay for livings costs, education and any additional classes. Living in New York or LA and being able to concentrate on getting parts of training rather than having to make money would be a huge boast.
Maybe at the next stage getting their kid an agent or manager who has contacts and experience to get their kid the roles.
Perhaps you mean throwing a few thousand dollars at student-level films to ensure their kid gets an important part. I guess maybe some will write 6 (7?) figure cheques to get their kid a part, but that probably doesn't happen often.