it's Metamask, Electrum, MEW, Trust, Coinomi, Atomic, or any other program you consider a wallet.
It provides the option to produce a seed phrase or private key when you install Metamask.
Other programs like Trust, MEW, and Atomic may all access your ETH if you use the same seed phrase across them all.
Therefore, the next time you download a wallet app, you won't need to create a new seed phrase; instead, you can import the one you already have to manage your current funds across different apps.
You seem don't understand importance of mnemonic seed, private key and risk when you import your private key or mnemonic seed.
When you do it, do it offline.
When you are considering to import your wallet mnemonic seed to a website, a wallet software, you must know you are leaking it to a third party if that website or wallet software has back doors.
I advise you don't import your wallet mnemonic seed to any wallet software if you want to do it to have an experience or to satisfy your curiosity. It's risky.