Answering ambiguity with 2 answers..

There are stem raisers that clamp on in place of threadless stems,
onto the fork steerer tube.
and then you relocate the existing stem onto the top of the stem raiser..
+ there are stems with a much greater Up angle, to raise the bars , that way.

Also, to accomplish something like that, there is a steel tube,
reduced in diameter at the bottom, that has its own quill bolt,
for threaded fork types, 1" and 1.125"
then you relocate your existing quill stem into the top of this added tube,
because the whole idea is the ID at the top is the same as the fork, it goes into,
but the OD at the bottom is reduced to fit into the fork.