>>82396532 (OP)
you're going to have a bad time. minecraft doesn't lend itself to this shit because you'd have to make it huge to get enough detail out of blocks.
you're better off doing it in Vintage Story creative mode, that has native block chiseling. still it would take a fucking long time for something this ornate.
just make a shitbox castle like everybody else before you try to make some fuckhuge shit.