Good day ahanif,
Do you have a copy of the 45001 standard? Please read the A.6 Planning section, page 28 in the Annex. It lists many examples of opportunities. A.6 in 14001 (page 22-23) gives a discussion but provides fewer examples. Please read both of these standards' Annexes, they are very informative.
An online definition of criteria stated:
a principle or standard by which something may be judged or decided.
"the launch came too close to violating safety criteria"
Criteria is included in ISO 14001:2015's requirements for aspects and impacts as well as operational controls, but not for planning actions for risks and opportunities. Criteria is also included in ISO 45001:2018's section (184.108.40.206, page 30) Assessment of OH&S risks and other risks to the OH&S management system, but not in 220.127.116.11 for Assessment of OH&S opportunities and other opportunities for the OH&S management system.
And so, while I would question if you must have criteria for the purposes of certification because both standards do not specifically require criteria for opportunities, for sound management purposes it still seems very sensible to define how you will decide which opportunity to pursue.
I hope this helps!