Since the first lockdown hit over here, I've seen nearly all of my clients in online appointments and so far I haven't encountered any issues, it's just as effective in terms of results. Some people prefer a face to face appointment but I've actually found most of my clients prefer the comfort and convenience of having their sessions at home.
From a client point of view as well, I had a couple of online sessions with a psychiatrist earlier in the year in order to get my ADHD diagnosis and it was great, I actually preferred it to a face to face session as I didn't need to waste time travelling or deal with stuffy waiting rooms.
One thing I will say is to make sure you have a solid internet connection and a decent quality microphone and test it before you connect, particularly important if you're using your phone. Other than that, check out the reviews and try to have a brief initial conversation with the therapist to get a feel for the way they work and what they may be able to offer you.
Many therapists specialise in several different areas, some are experts in a particular niche. Unfortunately, it's a bit of a lottery to find a good one, but as far as the online aspect - you're not limited by travel distance so cast your net more widely, perhaps even consider therapists from different countries if they are experts (many therapists will take on international clients). Above all else, set out clearly what you ultimately want to achieve from your therapy sessions before you start looking, knowing what you expect from a therapist in advance will not only help you more readily find a therapist who specialises in what you need but it allows your initial sessions to be more focused and tailored.