Our first love language is physical touch. As babies, touch tells us that we are safe and warm and loved. Your kiddo likely still needs a lot of physical touch. Hug and kiss them, snuggle them when you read or play, roughhouse with them.
You can also ask them how much physical affection they need. For example:
“How many kisses do you need to fill your love tank this morning?”
Whatever the answer, immediately and playfully give them that many kisses. Starting this practice now will pay off in years to come, as they may become more closed off to your physical affection but will still need it.
Also, pay attention to incidental touch. If your kiddo is not particularly huggy or snuggly, but comes over and stands next to you touching your arm, sustain that physical connection, only ending it when they move away.
While maintaining warmth and affection, it is always important to respect your child's boundaries and show them it's ok to say 'No' to any touch they don't like. Tickling especially can often become overwhelming for kids, as can roughhousing. Any time they say 'Stop' or indicate a boundary, in addition to stopping immediately, you can also reinforce their rights, such as:
"Ok, I stopped! Now I now that you don't like your hair ruffled that way, and I won't do it! You're the boss of your hair."