[Feature request] Make it easier to specify spacing in between titles and subtitles

I really appreciate the subtitle parameter within Plotly Express charts. However, I'm finding that, when I use title_y to update the title's location, the subtitle's location doesn't follow accordingly. This can result in unsightly gaps between the title and subtitle.

Would it be possible to add a subtitle_y dimension that would let me adjust the spacing between title and subtitle elements? I suppose subtitle_x would be handy also in case some users want a horizontal offset between titles and subtitles.

Here are some screenshots for reference. First, in this chart, I'd like to move the title and subtitle up to increase the spacing between those elements and my legend:

I can set title_y to 0.98 to move it farther from the legend; however, the y position of the subtitle moves up only a little, thus increasing the gap between the two.

If there were a corresponding subtitle_y parameter that I could adjust, I would be able to easily resolve this issue. (In the meantime, I can get around it by creating subtitles via add_annotation.)

Thank you in advance for your consideration and help!

从 Plotly Express 的副标题和标题定位行为入手，尤其关注 title_y 如何影响副标题；将其与当前使用 add_annotation 的变通方案进行比较。当用户可以分别控制副标题的垂直和水平偏移，且不会出现不需要的间距，并且该行为已有文档说明和适当的检查覆盖时，即视为完成。