- Edited
Based on your stated goal, a VPN alone without custom DNS will be fine (IMO). The perk of custom DNS is to stop telemetry of things like apps. When you open an app there is a high probability that its connecting to the internet in multiple ways, some of those is because it has to to work, others are because its sending off telemetry about usage and other things. Some people don't want telemetry sent off, those people use something like nextDNS to really tighten down. It doesn't sound like you are concerned about this, which is no big deal.
Your VPN will put your traffic through an encrypted tunnel, it will handle your DNS requests, and will hide your IP. If that's all you're looking for (which that seems to be the case) then just stick with the VPN only.