Asterisk will use early media if it receives it and knows where to send it.
Whilst there is a common mistake of starting dialplans with Answer, which will ensure that ringback is sent as normal media, if the downtream system sends ringback as early media, and Asterisk has received SDP, it is likely to forward it to the caller.
If you have the choice of late offer SDP, in the SIP client, and don't answer, Asterisk will have nowhere to send any early media. (If the downstream UAC only uses early media for ringback, this means the caller will not hear anything. In any case, most devices do not use late offer SDP.)