In order to apply for government colleges of Karnataka you have to fulfil below criteria

You must have studied and passed from a recognised institution situated in Karnataka. The academic study from a state institute should be for a minimum period of 7 years. You should have appeared/passed either SSLC/10th standard or 2nd PUC/12th standard exam from Karnataka according to the eligibility criteria of KCET.

If you don't fulfil above criteria you can appear in COMEDK exam to take admission in private coleges of Karnataka.

To know about COMEDK you can refer below link

https://engineering.careers360.com/articles/comedk-uget

Good luck!!