Hi @Anonymous ,
Do you want to trigger the flow only if when status is changed to "booked"?
Could you tell me the data type of status field?
I assume that it is an option set.
Actually, you just need to add a condition to compare the option set's value.
I've made a similar test for your reference:
1)create a new option set named status:

2)check the "booked" option's value, click "..."->view more.

3)the flow:
trigger "when a record is updated"
condition:
fieldname(in my test the field name is also status) is equal to 231670002
//231670002 is my "booked" option's value, please replace it with your "booked" option value, remember to remove "," in it.
yes: action: send an email

Then, only when you update the status to "booked", an email will be sent.
Best regards,