Caso esteja utilizando a lib openzenzepelin veja a implementação da extensão ERC20Capped.

MyToken.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.18;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Capped.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

contract MyToken is ERC20Capped, Ownable, ERC20Burnable {
    constructor(uint256 cap, uint256 initialSupply)
        ERC20("MYTK", "MTK")
        ERC20Capped(cap * 10**18)
    {
        require(initialSupply <= cap, "TOKEN Capped: limit exceeded");

        //default 18 decimals ERC20
        ERC20._mint(msg.sender, initialSupply * 10**18);
    }

    //lembre-se : mint 18 decimals
    function mint(address to, uint256 amount) public onlyOwner {
        _mint(to, amount);
    }

    function _mint(address to, uint256 amount)
        internal
        override(ERC20, ERC20Capped)
    {
        require(
            ERC20.totalSupply() + amount <= cap(),
            "TOKEN Capped: limit exceeded"
        );
        super._mint(to, amount);
    }
}