There are two marketplace modules you could look at:
Graph editor: https://marketplace.mendix.com/link/component/98525
I believe there is no such widget readily available.
See the response to this idea (an old one but the response is probably still valid) https://forum.mendix.com/link/ideas/372
If you would decide to create a widget yourself, maybe looking at the following widget could give some inspiration on how to approach it: https://docs.mendix.com/appstore/widgets/signature
And maybe you can find a way offer your users a jump to Word or something equal to do the editing there and store the result in you Mendix app? Creating a widget with this kind of functionality can be tricky and expensive, depending on the requirements
I hope this helps.
Thank you very much for your quick reply. Understood that there seem no such widgets in platform and market place. While I am considering the workaround as you proposed involving external rich client tools like MS Office too, one of customer requirement is to show in on Mendix. I will continue to investigate other options including making new widget and talk to the customer which one they think is best (or even unacceptable).