It sounds like you're good with kids of all ages and I was hoping for advice. I'm going to meet my partner's nephews and niece next month for the first time (all under the age of 5) and I'm anxious about it because I was an only child and I've spent very very little times around kids. Do you have advice on how to make small people like you?
Friend, I have excellent news for you: small people are big people with no filter and less practice in modulating their voices. It is usually very easy to sort out what they like/dislike and then just do the things they like. So my basic advice is as follows:
1. Treat them like drunk adults.
A. Talk to them like they're adults--ask them questions about their interests/toys etc. and seriously respond to their answers. None of that baby talk shit.
B. Give them autonomy--ask if it's ok before picking them up or hugging them or helping them put on shoes (unless they're going to hurt themselves and you need to intervene of course).
C. Don't be demeaning. Try not to laugh if they say or do something embarrassing. If they're hurt, validate that they're hurt and scared, and don't try to tell them they're fine. You have a whole lot of context they do not. Try to meet them where they are.
2. Find a thing they like and do it. Over and over again. Until they get bored/tell you to stop. A good way to start this process is to ask them to give you a tour of their room or ask them to show you their favorite toys. Example from last week: 3 yr old immediately showed me his car collection and laughed uproariously when I drove a toy car up his back, over his head, and then booped his nose with it (while making the appropriate sounds). After the first time he said "AGAIN" so I did this...probably 50 times over the next 10 minutes (and mixed it up by occasionally saying it was my turn--we gotta encourage sharing, you feel--and having him drive the car on me) (We also go to work on using gentle hands for nose boops. The first few were a bit rough, lol). But the point is, he laughed SO HARD every time. And then decided I was good people and took things from there, telling me he wanted to play "fix the plane" in which a plane needs fixing, I bring it into him, and then he fixes it. This lasted another 20 minutes. Small kids are very much about the thing they're about. If they're having fun doing a thing, just keep doing it, until they indicate they're done. A lot of adults will try to hurry kids along when the adult gets bored. Give the kid the space to set the time limits on things they enjoy for once and they'll adore you for it.
3. Thank them for their time. Like adults, kids love being appreciated and getting good feedback. I say "thanks for letting me play with X toy, I really like it." I say "thanks for showing me how X thing works, that's really cool." I say, "thanks for holding my hand while we walked through X place, that made me feel safe." And always at the end of the day/night I say "thanks so much for playing with me, I had a lot of fun spending time with you." Kids eat that shit up.
Also PS. Don't do that bend over with your hands on your knees thing. I don't know a single kid who likes that. To get on their level, kneel, crouch, sit or lay down. Don't loom.