In Chargebee’s Customer Portal, it is possible to group plans based on their billing interval.
To enable grouping of plans based on it’s billing interval, go to Settings -> Hosted Pages Settings -> Customer Portal -> Allowed Actions and under Allow Users to Change Subscription, select the option Group Plans based on Billing Interval; Screenshot is below for your reference.
Click on Update once changes are made for them to take effect.
Doing this will group the plans in the order of:
Below is a screenshot for your reference: