Y'all what do you do about a 4 year old that when she has to pee she just stops and pees on herself…

Y'all what do you do about a 4 year old that when she has to pee she just stops and pees on herself wherever she is this happened to me earlier with my daughter we were out walking and we were going back to the truck we are right at the truck she tells me she has to pee and I told her ok please wait for mommy well be home in just a second cause I could walk to the park from where I live and she goes ok I can hold it so I praised her for agreeing with me and then she stops not 30 seconds later and just pees all over herself and she watches herself do it and laughed I made her change clothes spoke to her about it being bad to pee on yourself cause it's ucky and I put her in timeout after I made her go pee now when I asked her why she did it she said cause she was mad at the heat so as far as I know I've done all I can do but I would like some tips on how you ladies handle the situation cause there's no bathrooms at this park