I do the girls leggings from cat and jack. They run slimmer and have more color choices.

My son is tall and skinny and does better with Carter's kid sizes- 4 or 5 instead of 4t/5t. They also usually have an adjustable drawstring waist also.

Carters/osh kosh make them and so do Cat and jack at Target. Just search “pull on”. I don’t like the Ones from lands end—even slims had so much fabric they were like sails.

Lands End Slim sizes - perfect for my similarly portioned kid. They have elastic-baked waists (at least to 4S), so my kid just pulls them up. He's 75th% and just a few days away from being 5, but the 4S from last year still fit him length-wise (though TBH if I were buying new I'd get 5S so he'd get more wear).

Primary. Their pants run tight and they have nice joggers.

He is 4, almost 5. I need to shop for long pants because it is getting cooler. His leg lengths are 5T but his waist measurement fits 3T or 4T. He does not do zipper or button pants yet, so pull on with flexible waist bands. Recommendation,please.