The global picture has largely normalized: most countries have dropped COVID-specific entry requirements, meaning no tests, no vaccination certificates, no quarantine, and no health declaration forms for the majority of travelers. The pandemic-era infrastructure of passenger locator forms has mostly been dismantled.
That said, don't treat this as guaranteed for any specific trip. A few countries retained health declaration systems or fold a health question into their digital arrival cards, requirements can differ for arrivals from particular regions during outbreaks, and countries have shown they'll reintroduce measures quickly when a new variant or other disease raises concern. Transit countries count too, not just your final destination.
So the reliable routine is a quick check shortly before booking and again in the week before flying: the destination's official immigration or health ministry page, your own government's travel advisory for that country, and your airline's travel requirements tool, since airlines enforce entry rules at check-in.