Can I use 0w 30 instead of 0w 20 engine oil in Honda wrv deisel model of 2019?

This probabaly isn't a great idea.

Different people will tell you different things as to whether it will cause damage, how quickly it will cause damage, or how bad the damage will be, I'm not going to comment on any of these. The fact of the matter is the people who designed the engine have tested different oils and concluded which one is best.

For example more viscous oil may put more strain on an oil pump than it was designed for, or may not fit into smaller gaps in the engine as easily as less viscous oil.

I'm not sure where you are in the world, but in the UK, EU and USA finding the correct grade shouldn't be too tricky. Amazon sell 0w-20 from Total, Castrol, Mobil-1 and Shell for example.

Hope this helps!

Stick with owner's manual unless you are in an emergency situation. 0W-30 covers a wider temperature range than 0W-20 and it causes no harm in terms of viscosity but 0W-20 is a thinner oil and has been designed with economy and fuel consumption in mind. I think for warmer climates, you can use 0W-30 instead of 0W-20 safely.