When an IRA or 401K is rolled over to another provider, your investments are typically sold, a check is issued, and sent either to (a) You or (b) the new institution.
I would caution initiating a rollover right now due to extreme volatility. Let’s say that your old plan is liquidated today, right after a 10% drop. The check is mailed out in 5 business days, you receive it in another 3 business days, and forward it to your new institution who processes it in 5 business days. That’s 13 business days in which a lot of swings may have taken place, and with funds being liquidated you may have taken a massive loss. I generally don’t recommend timing the market, but with rollovers you are out of the market for a few weeks, it may be wise to keep your funds in the current plan and wait to roll over until the volatility has subsided.