If the main thing you're concerned about is online multiplayer, then yes, all accounts on a single PS4 can play online if at least one if them has an active PS Plus subscription, and that PS4 console is set as the PS Plus account's "Primary PS4."
From Sony's FAQ:
PlayStation®Plus benefits available to other non-subscribing users on your Primary PS4™:
- Online multiplayer (subject to any parental control settings on sub accounts)
- Play downloaded games purchased with PlayStation®Plus discount
- Play downloaded IGC games
PlayStation®Plus benefits not available to other users on your Primary PS4™:
- Purchasing PlayStation®Plus discounted products from PlayStation Store
- Online game save storage
- Auto patch download
- PlayStation®Plus exclusive early access to game trials