Question about sim cards

[ThisLoftyLilacShark]

I have an iPhone but I want to buy a non-smart phone for when I want to have an internet detox. I know there’s restrictions I can set but I just find myself turning them off. Will it work if I just put the SIM card from the iPhone into the non-smart phone

Don't know if Iphone setups/sims work differently but I think the non-smart phone would need to be 'unlocked' first as some phones are pre-set to only accept a certain provider's sim (eg O2, EE, vodaphone).