Hi @Willo,
Yes, it could be achieved by using WDL function in flow.
Say your email body would be always the following format:

Then you could create a flow likes below. In this case, I will show how to extract the subject from the email body, please take it for a reference.
The flow is triggered by When a new email arrives, then convert the email body from Html to text.
In action Compose, use the code to get the total length of the body:
length(body('Html_to_text'))
In Compose2, use the following code:
add(indexOf(body('Html_to_text'),'Subject'),9)
In compose3, use the following code:
indexOf(body('Html_to_text'),'Start time')
In Compose4, use the following code:
substring(body('Html_to_text'),outputs('Compose_2'),sub(outputs('Compose_3'),outputs('Compose_2')))
It works fine and the subject can be extracted from the email body successfully.


More details about the functions at here:
https://docs.microsoft.com/en-us/azure/logic-apps/workflow-definition-language-functions-reference
Best regards,
Mabel Mao