If you are flying a 737 with auto-rollout just press the autoland status recall button once the IRS's are aligned and if it comes up empty you are good for LAND 3. If it come up as NO LAND 3 you still can do a normal autoland in LAND 2 configuration (fail passive) which still allows CAT III operation including automatic rollout, only if it says NO AUTOLAND you cannot do that.
That said on planes without those neat status messages on the upper DU we still get a placard installed from maintenance if the plane has a degraded autoflight system stating CAT II or CAT I only, if no placard is present normal operation, e.g. CAT III, is possible.