Requirement: Power automate flow creation using if expression variable
In Power Automate Click on +create>Instant flow> select the Manually triggered Flow> provide a name for the flow> then click on create button
Now click on Add input and select Number field for 2 numbers.

Power automate if expression variable
Next click on the next step and select Initialize variable action, then provide the variable name, type as a string, and in value write the below expression.
if(equals(triggerBody()['number'],triggerBody()['number_1']),'Yes','No')

Microsoft Flow if expression variable
Now click on the save and to run the flow enters a value in the number field.

MS Flow if expression variable
See the expression returns Yes, because 09 and 09 are equal.

MS Flow if expression variable
See the expression returns No, because 16 and 09 are not equal.

MS Flow if expression variable