Examples of bit lengths of different integer values: https://go.dev/play/p/gLZKA9B233I

int_bits.go

package main

import (
	"encoding/binary"
	"fmt"
)

func main() {
	// subtract 1 from each answer since we're counting zero also
	fmt.Printf("%d bits = %8b = %d\n", 2, byte(1<<2-1), 1<<2)
	fmt.Printf("%d bits = %8b = %d\n", 3, byte(1<<3-1), 1<<3)
	fmt.Printf("%d bits = %8b = %d\n", 4, byte(1<<4-1), 1<<4)
	fmt.Printf("%d bits = %8b = %d\n", 5, byte(1<<5-1), 1<<5)
	fmt.Printf("%d bits = %8b = %d\n", 6, byte(1<<6-1), 1<<6)
	fmt.Printf("%d bits = %8b = %d\n", 7, byte(1<<7-1), 1<<7)

	// Multiple bytes
	fmt.Printf("%d\n", 1<<32-1)

	fmt.Println("signed")
	// Max values (signed)
	fmt.Printf("%20d %08b\n", 1<<7-1, encodeToBytes(1<<7-1))
	fmt.Printf("%20d %08b\n", 1<<15-1, encodeToBytes(1<<15-1))
	fmt.Printf("%20d %08b\n", 1<<31-1, encodeToBytes(1<<31-1))
	fmt.Printf("%20d %08b\n", 1<<39-1, encodeToBytes(1<<39-1))
	fmt.Printf("%20d %08b\n", 1<<47-1, encodeToBytes(1<<47-1))
	fmt.Printf("%20d %08b\n", 1<<55-1, encodeToBytes(1<<55-1))
	fmt.Printf("%20d %08b\n", 1<<63-1, encodeToBytes(1<<63-1))

	fmt.Println("unsigned")
	// Max values (unsigned)
	fmt.Printf("%20d %08b\n", 1<<8-1, encodeToBytes(1<<8-1))
	fmt.Printf("%20d %08b\n", 1<<16-1, encodeToBytes(1<<16-1))
	fmt.Printf("%20d %08b\n", 1<<32-1, encodeToBytes(1<<32-1))
	fmt.Printf("%20d %08b\n", 1<<40-1, encodeToBytes(1<<40-1))
	fmt.Printf("%20d %08b\n", 1<<48-1, encodeToBytes(1<<48-1))
	fmt.Printf("%20d %08b\n", 1<<56-1, encodeToBytes(1<<56-1))
	fmt.Printf("%20d %08b\n", uint64(1<<64-1), encodeToBytes(1<<64-1))

}

func encodeToBytes(v uint64) []byte {
	buf := make([]byte, 8)
	binary.BigEndian.PutUint64(buf, v)
	return buf
}