Clarification Needed Regarding Penalties for Estimated Taxes

I keep hearing language around a "late payment penalty" or a "underpayment penalty" or an "estimated tax penalty." Ideally it doesn't come to fruition but should a penalty be imposed by the IRS, how does that get communicated to the tax payer? Let's say a penalty is incurred in the 2025 tax year - does that then show up in 2026 (when filing 2025 taxes)? When/how are you informed if you owe a "penalty"? Thank you!