No, no legitimate casino will ask you for $100 for account verification.
If you miraculously won some insane amount of money from a no-deposit welcome bonus, that is also a strong indicator of a scam. Legitimate casinos limit the maximum withdrawable amount from such bonuses, usually to somewhere between $50 and $150.
As Afi4wins mentioned, casinos generally require one deposit before they process the first payout. However, a minimum deposit is sufficient, which is usually in the range of $10–$20.
Search for the casino on AskGamblers, and if you cannot find it featured on the site, you should be extra cautious. That does not mean a site featured there is automatically trustworthy, nor does it mean a site not featured there is automatically a scam. Still, it is a good starting point.
If you actually shared the name of the site, we could tell you for sure whether it is a scam or not. However, based on everything you have told us, which is not much, it is most probably a scam. Do not pay them.
@mhjahidkb Hi there and welcome to the forum.
In most cases, legitimate casinos would only require a minimum deposit of around 20 - 25 EUR to verify and process a new account.
There have already been so many reports of crypto casinos demanding a 1st initial $100 deposit just to get the new account verified, but more deposits would then be demanded just to get the withdrawal claim processed - needless to say, most of these crypto casinos are scam ones!
Horatio: Probably not this week!
Icy: Yep, in contests or payments the conditions are almost always "sp@nked or be sp@nked".
Shannon: I can't help but overhear you guys are waiting patiently but would one of you mind rubbing sunscreen lotion on my back?
Icy: 👀
Icy: We'll keep this between Cocopop3011. ☺️
Horatio: Icy, Coco's coming back you have to hurry!
Icy: Almost finished. There, nice and lubricated.
Shannon: Thank you Icy 💋
Icy: Hush hush remember. 😉
Cocopop3011: Hey guys, I have the schedules for the upcoming contests!
Icy: Oh goodie, what's on the menu?