If you have a service animal rather than an emotional support animal and IF the host doesn't have pets themselves and isn't a homeshare host with say pet allergies then they need to accept your booking @Max2246
I would imagine in most scenarios you would prefer to find a host that is pet friendly and therefore set up to accommodate service animals. If there are no pet friendly listings in the area you want to stay in, and you have a service animal that you confirm you will keep with you at all times, then absolutely flag with Airbnb that the host has denied your booking because you have a service animal.