No. Third-party applications like Avalara will help in applying the appropriate tax rates for your invoices. However, the tax configuration changes like the addition of UK as a seperate region, other settings like manage checkout prices, exemption notes and so on, as described in this document must be done for the UK region and the EU region as applicable for your business.
With Chargebee handling invoices for your business and automating the tax application, it is important that you keep your tax configuration in Chargebee up to date.
If you are not making necessary changes for Brexit in Chargebee, your invoices will continue to carry outdated tax rates that will not comply with the Brexit laws. You could end up charging your customers wrongly, paying fines for not following the taxation rules, all of which could have a bad impact on your business.
To keep your business safe and to ensure uninterupted invoicing, make sure that you keep Chargebee updated by making the Brexit changes.