Yes. VPC networks are completely isolated from both other customers and other VPCs on your own account. See here for more details:

https://www.digitalocean.com/docs/networking/vpc/

It’s also worth pointing out that DigitalOcean private networks provided account level isolation since July 18, 2018. The big changes with the release of VPCs are:

• You can create multiple VPCs that are isolated from each other
• You can define the IP range for your VPCs yourself