Hi Harshit, yes you can learn all these through online courses itself. It all requires an interest amd will to learn. But an degree in b.tech IT can be a very powerful profile while going for future jobs or any sector. These languages can be learnt always from many online portals like Udemy, Coursera, Code Academy etc which provide many courses and resource materials. There are also institutes outside who can give you more practical touch to these courses and can help you grasp things quickly and with more practical Knowledge. I would say pursue a degree in B.Tech IT and side by side join institutes or online courses which help you to support you profile successfully.

Hello sir
Yes you can do but without b tech another option according to my suggestion please do the back computer science stream meanwhile you learn the course which ever you like the most like app development and as well C programming java programming and lot of programming languages are there based on your interested you can proceed into it
Good luck sir