The UAE restricts VoIP calling — WhatsApp voice and video, FaceTime audio, and Messenger calls — on local connections. Tourists discover this the day they land, mid-call.
The detail that decides it
Travel eSIMs route your internet through a gateway that may sit outside the UAE. If the plan's data breaks out through, say, a UK or Singapore gateway, app calls work normally with no VPN. If it breaks out locally, the same blocks apply as on a local SIM. Good stores state the breakout location per plan — ask before you buy if it isn't shown.
Everything else
Coverage in Dubai and Abu Dhabi is world-class (5G in most of the city, Metro tunnels included). Keep your local number active in the second SIM slot for calls and SMS, and use the eSIM purely as your data line.