@terran is right; it's a matter of plan policy. For example, my company's plan allows one in-service withdrawal, up to 50% of the plan value, at age 50.
The other thing to look for is if your plan has a brokerage window. (or lobby your HR for it) Fidelity calls this BrokerageLink. I can invest in (nearly) anything that I could in an IRA. Note: you will still be subject to the 401k's plan expenses with a brokerage window. Since you are using the retail platform, this will become a distinct fee, because they can't roll it into the fund fees.