How to contribute changes to plugins?

I’m interested in contributing an improvement to the S3 plugin, but am having trouble getting my changes to build locally. I’ve gone through the Development Setup guide, but there is no information related to the plugin system.

I’ve tried making a simple change in plugins/s3/index.ts, setting one of the fields to required: false. Then I did the following:

cd packages/nc-plugin
npm run build
cd ../nocodb
npm run build
npm run watch:run

…and in another console tab:

cd packages/nc-gui
npm run build
npm run dev

…but the change does not appear in the S3 plugin modal at localhost:3000/dashboard#/account/apps

Can anyone point me in the right direction here?