Степан И

package main

import (
	"fmt"
	"time"
)

func main() {
	t := time.Date(2022, time.June, 20, 0, 0, 0, 0, time.UTC).AddDate(0, 0, 10)

	fmt.Println(t.String())

	t, _ = time.Parse("2006-01-02", "2022-06-20")

	fmt.Println(t.AddDate(0, 0, 10).String())

	t = time.Now().AddDate(0, 0, 10)

	fmt.Println(t.Format("2006-01-02"))
}

2022-06-30 00:00:00 +0000 UTC
2022-06-30 00:00:00 +0000 UTC
2022-06-30