Can you change a kids bike into a trick bike?

Answer 1

Don't really know what you mean by a trick bike. But generally kids bikes tend to be rather crappy. Kids will outgrow their bikes fairly fast, which makes the parents unwilling to spend money on them. As a result, they're often heavy, with poor parts poorly put together.

For a trick bike you'll want something lighter, stronger and more suited to hard riding.

And as bike parts are least expensive when bought as a complete bike it doesn't make sense money-wise to spend a lot of money on a complete bike make over. Better then just go for a new bike.