The general consensus is topping is not ideal for autos unless your well versed in topping. If so go for it. Its just a matter of making sure yiurbdo it at a time where the plant wont take much time to recover from it and become stunted.
If you will top autoflowering plant it may not grow enough before going blooming. You could top photoperiodic plants because you can control the duration of the vegetative period.