And if you are in NAV mode, there’s an Airbus “Gotcha” to be aware of. Be careful allowing the aircraft to automatically engage approach mode upon passing the DECEL point. This point is shown on the Navigation display as a Magenta “D” with a Magenta circle around it.
At this point, if you set the APPR brief page on the MCDU, the aircraft will activate approach mode and slow to the VAPP speed provided by the FMGC which you would have prepared by entering the appropriate data in the MCDU APPR page before TOD.
If this happens, the gotcha is that you may still be a good distance from the airport and slowing to approach speed. Typically, you would either have speed restrictions or ATC (real ATC, not sim) would assign you a speed. For instance, slow to 210 kts. At that point, usually before the “D”, you would PULL the speed knob and dial in a SELECTED speed per ATC.
Once ATC clears you for the approach - ILS or visual - you would then PUSH the speed knob to go back to managed mode. If you are past the “D”, the mode will switch to APPR and the aircraft will begin slowing to your VAPP speed, as able.
Getting slowed for approach really starts during the descent and requires energy management all the way down so you don’t arrive at your approach gate with excess energy to dissipate.
Here’s a cool reference on setting up for the descent phase and the approach brief setup: https://www.smartcockpit.com/docs/A320-Descent.pdf