It definitely adds to the bundle size, but how much it adds depends on your implementation. This discussion on the topic is pretty interesting [0]. One comment

It definitely adds to the bundle size, but how much it adds depends on your implementation. This discussion on the topic is pretty interesting [0]. One comment from that discussion says “it is possible to double to the size of your source code”. [0] https://dev.to/haruanm/does-typescript-increase-the-bundle-size-of-a-project-mp4 https://dev.to/haruanm/does-typescript-increase-the-bundle-s...