Hi @KT61
For demo purposes, I have created a Choice field like below, which has 3 three options

Choice1, Choice2, Choice3
Now my requirement is whenever someones changes choice value to Choice 2 it should trigger the flow
So i have designed the flow like this below
First we will use trigger to start the flow when a item is modified.

Second we will use get changes in sharepoint to know what changes had happended in item since previous version like below

Here since field we are passing the previous version number by subtracting current version number of item by 1 using below expression
sub(int(trim(split(triggerOutputs()?['body/{VersionNumber}'],'.')?[0])),1)
Next we will use condition like this


This condition check whether the choice column has changed from its previous version and its current value is Choice2 using and operator.
If condition is True, in Yes branch we can add send email action to notify the change in Choices field column like below

Hope this helps
Mark it as solution if it resolves your query 🙂