Use a trusted messenger. If possible, transfer the OTP yourself.
Sending OTP keys over the Internet is usually not a very good idea because "the distribution itself won't deliver perfect security" and one must worry about "integrity and authenticity", as Maarten Bodewes has said. Moreover, it is reasonable to assume that using a OTP might attract some eyeballs, automated and otherwise, onto your traffic.
There is another option: steganography. But you are still going to burn a lot of your precious truly-random bits because you do not want to send any of your keys unencrypted.
An advantage of using a trusted messenger that is seldom brought up is how one can limit metacontent (metadata) during key exchange. Look at it as a security question and then a choice: what collection platforms are there likely to be, and does it matter whether I get on them or not?
Create your OTP on an air-gapped device that has never (and cannot) touch the internet or any other device whatsoever, then lose your phone and put the OTP in your future correspondent's hand.