go get github.com/worldline-go/trange

package main

import (
    "fmt"
    "time"

    "github.com/worldline-go/trange"
)

func main() {
    loc, _ := time.LoadLocation("Europe/Amsterdam")

    start, end, _ := trange.Day("2022-08-05", loc)

    // start 2022-08-05 00:00:00 +0200 CEST end 2022-08-05 23:59:59.999999999 +0200 CEST
    fmt.Println("start", start, "end", end)
}