This is the kind of tricky answers that can be turned into favour if pondered a bit.
If I have to roleplay as the hiring manager, and I am hiring for a jr position, and I get this kind of answer I immediately think two options:
1 - this person sure is confident
2 - this person have no idea what they are talking about.
For the first option, you need a strong proof to convince me that what you are saying is true, otherwise I will just have to trust you, and not everybody will unfortunately.
For the second option, I can think that you are still too inexperienced to understand how actually complex that topic might be, and thus be too over-confident.
In this situation what I suggest you to do is to bring the conversation on “your ground” and point me towards option 1.
So instead of the above I think a more appropriate answer would be
No I don’t. However I used [tech X] in the past for this project. I know it’s not the same, but they both share <common functionality / goal>. [Expand on your answer]
Some concrete examples.
You are applying for a company that uses Vue, but you have always used React.
No I don’t. However I used React in the past for this project. I know it’s not the same, but they both share a reactive system. I will have to learn the syntax, but I hope to be proficient soon. Moreover the routing system/framework …etc etc [you get the point]
You are applying for a company that uses SQL but you used NoSql.
No I don’t. However I used DynamoDB in the past for this project. I know it’s not the same, but in this project I had to set up a multi-index system to speed up queries. Also I had some brief experience with collection filtering and data aggregation. It will be a challenge but I know I can […etc…etc]
As you can see then the goal is to say “no, but I know what I am talking about” to give confidence that you will able to learn it.
But ultimately for how much it is hard to do interview, just try to be yourself and let your personality shine