Yes, Chiang Rai Mae Fah Luang International Airport (CEI) has a lounge, though it is a modest, single-terminal facility rather than anything on the scale of a major Thai hub. If you searched Chiang Rai airport lounge expecting Suvarnabhumi-style variety, the honest picture for this regional-international gateway to Thailand's far north is smaller and simpler.
The lounge at CEI is a small pay-in space rather than a branded flagship, with basic seating, soft drinks or light snacks, and a quieter corner set back from the gate area. It is not built around airline elite-status tiers or a global lounge network the way Bangkok's airports are, so treat any Priority Pass or premium credit-card lounge program coverage here as unconfirmed rather than assumed. Check your program's current directory for Chiang Rai specifically before you count on it.
Suvarnabhumi Airport in Bangkok, several hundred kilometers south, is the real comparison point: multiple airline and Priority Pass lounges running at a scale a regional field like Chiang Rai was never built to match. CEI instead exists to move travellers through Thailand's Golden Triangle region, where the country meets Laos and Myanmar along the Mekong, a role that shapes a smaller terminal and a simpler lounge picture.
Traffic through Chiang Rai climbs during the cool, dry Golden Triangle season, roughly November through February, when hill-tribe trekking and river-border day trips draw the heaviest visitor numbers and the compact terminal fills up accordingly. If you are flying through during those months, budget extra time rather than counting on lounge space to absorb the crowd. Outside that window, the terminal runs quieter and the modest pay-in lounge becomes a genuinely useful stop before boarding. Confirm current hours and access terms locally, since a facility this size can change without much notice, and do not assume the same amenities carry over from one travel season to the next simply because they applied on a previous visit.