Asterisk detects an inbound call with SDP a=recvonly to a SIP INVITE, how can asterisk initiate an outbound call with SDP a=recvonly to a SIP INVITE using Dial application? Asterisk is not a SIP proxy, it initiates always outbound calls with SDP a=sendrecv, regardless of a=recvonly in inbound SIP Invite.
You’d have to make code modifications in Asterisk to accomplish such a thing. If you’re asking how to do that, then you would need to identify where it is handled, how it flows through the core (which if I recall it doesn’t currently), and adjust things.