Pick the Scryfall oracle tags that define your theme, and Tag Tutor finds the Commander cards that pack the most of them.
Or start from a theme
Tag Tutor is a free tool for Magic: The Gathering Commander (EDH) players. Pick a color identity and the Scryfall oracle tags that define your theme, and it returns the Commander-legal cards that match the most of them, ranked so the cards hitting every tag rise to the top.
Oracle tags come from the community-run Scryfall Tagger project. They describe what a card actually does, sacrifice-outlet, landfall, reanimate, counterspell, instead of just its text. Tag Tutor searches across several tags at once and scores each card by how many it satisfies, which Scryfall's own search can't do.
Looking for a Golgari aristocrats deck? Select the br-adjacent green-black identity, add sacrifice-outlet and lifegain, and Tag Tutor lists every commander that does both, the strongest matches first. Try one of the theme presets above to see it in action.