You can specify a proxy server to use when connecting. The argument passed to setProxyServer will be passed to the --proxy-server= option of Chromium. More info here: https://www.chromium.org/developers/design-documents/network-settings#TOC-Command-line-options-for-proxy-settings
Browsershot::url('https://example.com')
->setProxyServer("1.2.3.4:8080")
...