The type of pool and the desired changes will direct the scope of the remodel project. If you are adding a feature, such as a waterfall or spa, then any pool can typically be modified to accept these new changes. If the change is more dramatic like changing the size or the shape of the pool there are limitations based on the original pool construction. Fiberglass and Vinyl pools really cannot be adjusted this way. Gunite pools can be modified, but the effect on the structure should be considered. More often than not, the best way forward is to remove the existing pool and start anew.