Hmm, this is an interesting request. You can target tags with .tag. You could do something like this:
.tag {
position: absolute;
left: 50px;
}
But the problem with the left property is that it is not going to be relative to the paragraph, it’s going to be relative to the section container, which spans the width of the pane. So the tag will move as the pane width changes.
I’m also not sure whether you want to apply this to all tags or just the first tag of a section, so you might need your rule to be something like .markdown-preview-section > p > .tag. There are other ways to target that first tag.
If you want to continue with Obsidian and custom css, I recommend reviewing this post https://forum.obsidian.md/t/getting-comfortable-with-obsidian-css/133 and other resources on the forum and in the help vault.