Related:
https://forum.obsidian.md/t/ability-to-resize-columns-in-tables/1553/4
My comment: as mentioned, you already have ability to control how tables are rendered by writing html code inside your note. But it could be useful to have separate Obsidian feature for this as well. The problem is that Obsidian should automatically convert markdown tables to html resulting unexpected changes to markdown documents. It’s not Obsidian’s duty to decide how well markdown is supported, their duty is to support markdown as documented officially in GitHub Flavored Markdown Spec. This means that native feature to change table column widths is impossible.