Upvote:5
No, there isn't. Taxis tend to be very regional and a few countries have even a nationwide service, never mind an international one.
Uber does have a "request car seat" option in a select few cities, but this is nowhere near global. (At time of writing, I believe it's limited to a few large US cities.)
https://help.uber.com/h/3abcbae1-132b-42a9-8277-0dab00fa3879