Lightning Web Component:

<template>
    <lightning-card title="Sample LWC Component">
        <lightning-input type="text" onchange={handleInputChange}></lightning-input>
        <lightning-button label="Open Flow" onclick={openFlow}></lightning-button>
    </lightning-card>
</template>

JavaScript:

import { LightningElement } from 'lwc';
import { NavigationMixin } from 'lightning/navigation';

export default class SampleComponent extends NavigationMixin( LightningElement ) {

    strRecordId;

    handleInputChange( event ) {

        this.strRecordId = event.detail.value;

    }

    openFlow() {

        this[ NavigationMixin.Navigate ]( {
            type: 'standard__webPage',
            attributes: {
                url: '/flow/Sample_Screen_Flow?recordId=' + this.strRecordId
            }
        },
        false // Replaces the current page in your browser history with the URL if set to true
        );

    }

}

JS-meta.xml:

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>52.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__Tab</target>
    </targets>
</LightningComponentBundle>

Sample Flow:

Flow Initial Screen:

Flow Input Variable to receive parameter:

Output: