Yes, it is possible to shift from an exclusive tax model to inclusive in Chargebee.
Note - the plan price will not be affected when you make this change.
For example, you currently have a plan price of $10 and a tax rate of 10%, the invoice amount would become $11($1 for tax). When you switch to “inclusive” tax, the plan price would remain $10 and it is assumed that the plan now includes the tax amount $10(Plan price $9.1+ tax amount $0.9).
To change the price type, navigate to Settings > Configure Chargrbee > Taxes. Refer here to know more about configuring price types in your Chargebee account.
You can change the plan price to reflect the tax inclusive prices. Refer to this solution article for the details on changing the plan price and how this would impact existing and new customers in Chargebee.