I'll focus on Bitcoin as does the OP. To generate interest your coins need to do some kind of work. You won't get interest simply by hodling in your own custody, at least not without doing something with them. Any other service that offers interest for your coins also has to do something with them and that's been pointed out here already. Usually you have to give up custody for your coins, let some service do something with your coins and pay you some interest for that risk. This all could go right but also the opposite could happen as shown by some examples from the past.
It should be clear by now that you don't get any interest for free.
If you strictly want to hodl in your own custody, it's your obligation to setup a secure environment, a secure computer for your wallet(s) that isn't used for everyday internet shit.
If you're not comfortable to maintain such a secure environment, a decent hardware wallet is recommended (Passport from Foundation Devices, BitBox02 from Shiftcrypto, Coldcard from Coinkite, ... (and no Ledger closed-source crap in my opinion) pay attention to transparancy of the hardware wallet manufacturer, closed-source firmware and wallets are a no-go for me and should be for you, too).
If you insist on safe self-custody and still want to explore the option to gain some interest from your hodled coins, Joinmarket could be an option which I consider rather safe. You can boost privacy of your coins if you understand the concept and you can earn some interest by offering your coins for coinjoins as a market maker in Joinmarket. I watch the Joinmarket project for a long time, understand the concept but I haven't used it yet as a market maker, simply because I have no coins to spare for it yet.
So, I can't tell from first hand experience how much the yield could be. You won't get rich for sure, but it could be better than getting nothing. And I consider it safe because you don't give up self-custody. A secure device is mandatory and I would say it's not an option for newbies. You need a good amount of understanding of basic concepts of Bitcoin.
To learn basics and more head over to
https://learnmeabitcoin.com and work yourself through the pages. It's worth the efford!