That looks about right. You'll need to save that as a file named "com.google.Chrome.plist", create a new Configuration Profile, and then upload your "com.google.Chrome.plist" file as a part of the "Custom Settings" payload.
We're using this approach and identically to how @bumbletech explained it. Hope this helps :)
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>DeveloperToolsDisabled</key>
<false/>
<key>ExtensionInstallBlacklist</key>
<array>
<!-- ID for Google Chrome Extension - Storyful Multisearch -->
<string>chjbobecfbckiecmjcfacofliogmekcm</string>
</array>
</dict>
</plist>

We're using this approach and identically to how @bumbletech explained it. Hope this helps :)
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>DeveloperToolsDisabled</key>
<false/>
<key>ExtensionInstallBlacklist</key>
<array>
<!-- ID for Google Chrome Extension - Storyful Multisearch -->
<string>chjbobecfbckiecmjcfacofliogmekcm</string>
</array>
</dict>
</plist>

Goal: Force install a, b, c + Uninstall and block future installs of d.
Using this script, I hoped to achieve that but although it completed in Jamf, it did not uninstall d. Any suggestions?
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>ExtensionInstallForcelist</key>
<array>
<string>hdokiejnpimakedhajhdlcegeplioahd</string>
<string>glnpjglilkicbckjpbgcfkogebgllemb</string>
<string>kgjfgplpablkjnlkjmjdecgdpfankdle</string>
</array>
<key>DeveloperToolsDisabled</key>
<false/>
<key>ExtensionInstallBlockList</key>
<array>
<string>kbfnbcaeplbcioakkpcpgfkobkghlhen</string>
</array>
</dict>
</plist>
I haven't tried the force install yet but "ExtensionInstallBlocklist" will successfully block (although not uninstall) the specified extensions.
Tested it with this example and it works as expected to block already installed extentions and block future installs from the Chrome web store.
Note: The name of the key has changed since the original post.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>ExtensionInstallBlocklist</key>
<array>
<!-- ID for Google Chrome Extension - LastPass -->
<string>hdokiejnpimakedhajhdlcegeplioahd</string>
<!-- ID for Google Chrome Extension - ProKeys -->
<string>ekfnbpgmmeahnnlpjibofkobpdkifapn</string>
<!-- ID for Google Chrome Extension - Speedtest -->
<string>pgjjikdiikihdfpoppgaidccahalehjh</string>
</array>
</dict>
</plist>
You can whitelist Chrome extensions using a configuration profile. The provided code blocks all extensions by default and allows specific ones (Docs, Sheets, Slides in the example) through their IDs (found in the Chrome Web Store URL). Save this code as a .plist file and import it into your MDM tool (recommended) or a configuration profile creator app. Deploy the profile to your devices to enforce the whitelist. Remember to update the whitelist with any new approved extensions.
Hello everybody,
I want to block all extension expect the one. I create plist and deploy with conf. profile. Machine has pulled the profile. But user can still install new extension and keep use installed extension. Where is my mistake? Here is my the plist

Hello everybody,
I want to block all extension expect the one. I create plist and deploy with conf. profile. Machine has pulled the profile. But user can still install new extension and keep use installed extension. Where is my mistake? Here is my the plist

Whitelist and Blacklist are not the correct keys.
They should be
ExtensionInstallBlocklist
ExtensionInstallAllowlist
https://chromeenterprise.google/policies/#ExtensionInstallBlocklist