Using Apple Watch for visually impaired

Hello my father, if it is visually impaired, we got him a cellular Apple Watch for fall protection . The problem is when a phone call comes in on his Apple watch T hat’s tied to his phone. He can’t answer the watch because he can’t see the green answer button. Is there an alternative set up to answering a phone call on an Apple Watch by asigning the crown button ? Is there an app or any other way to make just touching the watch answer the phone?