I need to find a person who will be engaged in advertising the project (18+). I couldn't find any website that has telegram channels where I can buy ads. Do you know such?

for example telega(.)io but there is no 18+ channels :huh:  I found a couple of russian sites, but there is no translation into English and payment is only in rubles   :-/

Post in market someone will do it i bet

I will suggest you to visit some adult sites and sign up there and post a comments with your telegram link. So many users will join you for sure from there.

depends on what you're trying to sell. If yours are adult sites, try digging into some sports betting channel, typically they will offer ads services.

use ads on dodgy streams :P