@Lynn66
Not really sure what you are asking Lynn... so apologies if this is not the answer.
Hosts and guests, irrespective of whatever cancellation policy is in place, can discuss change of dates, cancellation, etc. A host can agree to refund accommodation cost in full (even if they have a strict policy in place).
However, what host can't do is impose a more strict cancellation policy than would be incurred if the guest followed AirBnB's policy. So, for example, a host cannot say: I have a strict policy with AirBnB, but I will also demand £x additional if you cancel last minute. AirBnB won't support that.
If you have a strict policy in place, then a guest who cancels at last minute will lose out and you will be paid in line with your strict cancellation policy. It's up to you to decide if you wish to refund them anything, or give them a discount on a future stay, etc.