Hello,
Yes definitely you will get good colleges even if you can't score 75% in 12th board exams but except NITs,IITs,IIITs and GFTIs.You can get VIT,SRM,COMEDK Colleges,UP Colleges if you can score very good marks in their entrance exams(VITEEE,SRMJEEE,COMEDK UGET,UPSEE,etc).All you need to do is to find out entrance exams list and apply for these accordingly.Prepare with ncert books and solve previous years questions.
https://engineering.careers360.com/articles/top-engineering-entrance-exams-in-india
Good luck:)

Of course you can but by clearing entrance exam in law field Clat,blat,ggsipu can be better option while for commerce also bhu bcom, Lucknow university, symbiosis,etc while for other fields their are lot more options that anyone neighbour or friends can explain