You can certainly just choose your focal length and leave it there - or - you can zoom through the app - or - you can get the Focus Handwheel and use that to bounce between focus, aperture and zoom. The hand wheel is a great accessory for this and is not terribly expensive. If you pick up the X5S without the lens it saves you $500 which many find useful to put towards the lenses they prefer to have vs just using the kit lens provided with the X5S (DJI 15mm). Here are a few links for you if you are interested:
DJI Focus Handwheel
DJI Focus Handwheel Bracket
DJI Focus Handwheel - Inspire 2 RC CAN Bus Cable - 0.3m
The other way to mount the handwheel is with a Secraft Tray. Here is a link to the Secraft Products we stock:
Secraft
You would need a Tray, Harness and an Easy Clamp. This set up is a little more expensive but it really help with the balance of your remote controller. The hand wheel adds some weight to either one side of your remote or the other and if you take your hands on the remote it will want to lean to the heavy side if you are just connected with the center clip on the radio.
Hope this helps - and if you decide you are ready to get any of it, we stock everything and ship same day.
Thanks!