Not at all, online wallet are the most risky because of various reasons like-
1. Hacking
2. Limiting Account
Unlike bitcoin core, you don't have any control over coinbase or the same types of wallet. Coinbase, in general, is an exchange and a wallet for the newbie who get trapped by them by google.
But they also have some security to restrict this like for hacking they have 2fa and login shield when the access happening from unknown device which may save lot of hacks.
Limiting account means don't have control over funds right,but this is good thing for the newbie who don't know what fee need to use for transacting so they get end up setting default fee from coinbase but newbies need to learn quickly about crypto wallets rather than trusting online wallets for long time.
Why comparing Bitcoin Core wallet to Coinbase? Its just like comparing apple to oranges (desktop wallet vs exchange wallet).
Its clear that which one is better hence, coinbase is an exchange and majority does know that if you store up funds on an exchange wallet which
you dont own the keys then you simply dont own those coins completely when you store it up there.