Sorry,I confused it with group limits.
After some research,I've landed on the same conclusion,a developer can't help you to break the 200 limit.
Q: How do I add people to my channel?
As the channel‘s creator, you may invite the first 200 members to your channel. Once the member count reaches 200, the channel is on its own. If it’s a public channel, it will have a username and a telegram.me/ link (e.g. t.me/telegram) – you can post this link on social networks, advertise it in magazines, or tattoo it on your back. If you have a private channel, you can send an invite link to your friends.
Please do not send channel links (or other unsolicited messages) to strangers. If they report spam from your account, you may be banned from contacting other people, however good your intentions.
Source:
https://telegram.org/faq_channelsI hope this answers your concerns.
Edit:
recently ive noticed some channels, add others people in their channels without permission of the users.
What you've seen is not channels but GROUPS,where admins add other people without their permission