In WWII a small number of German warships kept large numbers of Royal Navy warships occupied in searching for them. In another major conflict I wonder if it would be possible for some heavily armed warship (probably not a battleship admitedly) supported by oilers to tie down large enemy forces in a similar way? The ocean is vast and another Graf Spee destroying ships across a large area seems to be to be a possibility. How would we deal with this?
Use merchant raiders, not warships, warships are too obvious. Merchant raiders are much more effective because they can get close enough before revealing themselves to silence their targets before a warning can been broadcast. This gives them time to get away before warships can respond.
Large warships (battleships and heavy cruisers) can tie up more naval forces because there are fewer ships that can go one-on-one with them. But once located their ability to evade detection and tracking is limited, the net of forces seeking them then collapses inward and they are destroyed. They are best used as threats, like the Tirpitz, to tie up forces in case it sorties. This could be enhanced if there were multiple anchorages that it could move between to make it appear it was at sea, triggering a search and naval deployment while still safe. Odds are these vessels would never get the opportunity to fire on an enemy vessel.
The really effective vessels were merchant raiders with extremely long cruising ranges. The best were probably the WWI raiders Seadler (A 3 masted
sailing ship) and Wolf IV (A coal carrier, which gave her an
unrefueled range of 32,000 miles!). These ships could afford to go a long time between kills (which made them extremely difficult to track), constantly relocate their areas of operation (requiring more ships to cover potential areas of attack), and, given a couple days head start, the ability to out run naval pursuit by simply running them out of fuel. Neither was sunk by naval action.
And the best weapons were mines, which could close off entire areas to commerce long after the raiders had left. WWII raiders used moored and drift style contact mines, but more modern bottom sitting influence mines with long activation delays would be much more effective, and could even be deployed in anchorages or before hostilities commence undetected.