You can do this with Karabiner-Elements, but as noted this doesn't work everywhere — IIRC, it doesn't work in apps that don't have a "Paste and Match Style" menu item. Pure Paste solves this, as does Paste Plain Text.

If you use Raycast (highly recommended), you can also use its Paste As Plain Text extension: https://www.raycast.com/koinzhang/paste-as-plain-text

You don’t need any extra software to do this. You can reassign `⌘-V` to `Paste and Match Style` by running this in the terminal:

defaults write -g NSUserKeyEquivalents -dict-add 'Paste and Match Style' '@v';

I’ve been using this for years, and it works perfectly in most programs. If an app doesn’t have a `Paste and Match Style` option, its regular `Paste` command continues using `⌘-V`. But occasionally I want to paste an image and can’t because the `Paste and Match Style` command doesn’t work with non-text clipboard items.