Qatar airways SO type transition
 

I know start working in the QR start aircraft is A320 but I wonder that ctc cadet second officer permanently flight in A320? or can transition 777, 350.787, 330 ? If transition is possible when they can change to big aircraft approximately?

You will be 'locked' onto the A320 aircraft for a certain period after your training (1500 hrs) until you are able to switch your MPL to an ATPL. Then as any other pilot you are free to request to transfer to whatever aircraft providing they need you there ...

Does QR not require English language proficiency?

mean that during A320 second officer to build 1500hrs transfer ATPL and I can chage aircraft freely?

You can do yes, after 1500 hours though. The MPL locks you onto the specific aircraft type you trained on.

One thing I will say is though, and not to be rude, but you are required to obtain a specific standard level of English to be able to apply to the programme, make sure you have that before you travel to the UK for assessment to avoid disappointment.