You can visit these places:
silver Cascade waterfalls
Kurinji Andavar Temple
Kodai Lake Boating
Bryant and Chettiar Parks
Pine Forest etc.
If possible visit Berijam Lake. Don't miss out if you get that opportunity!!!!
Not sure about two-wheeler rentals, but there are bicycle rentals though, if you're interested.
I had visited Kodai 2 years back . its a beautiful place. https://www.holidify.com/places/kodaikanal/sightseeing-and-things-to-do.html
I hope this link can help you with places to see. so we were 5 of us and we had booked a package at madurai bus stop which included stay and sight seeing. and the per person cost was really cheap . there are many travel agents at madurai who can help you there make sure you bargain properly. have a lovely trip ❤️