Create a package called rs_rtab to run launch files:

catkin_create_pkg rs_rtab std_msgs rospy roscpp

Make folders for the launch files and the aruco pose estimation script:
mkdir launch

mkdir scripts

Mapping Mode:

<?xml version="1.0"?>

<launch>

    <!-- Include the RealSense camera launch file -->

    <include file="$(find realsense2_camera)/launch/rs_camera.launch">

        <!-- Pass necessary arguments if required -->

        <arg name="align_depth" value="true" />

        <arg name="enable_sync" value="true" />

    </include>

    <!-- Include the RTAB-Map launch file for mapping mode -->

    <include file="$(find rtabmap_launch)/launch/rtabmap_new.launch">

        <!-- Pass RTAB-Map arguments for mapping mode -->

        <arg name="rtabmap_args" value="--delete_db_on_start --Grid/NoiseFilteringRadius 0.15 --Grid/NoiseFilteringMinNeighbors 2 --Grid/DepthMax 3" />

        <!-- Pass the camera topics -->

        <arg name="depth_topic" value="/camera/aligned_depth_to_color/image_raw" />

        <arg name="rgb_topic" value="/camera/color/image_raw" />

        <arg name="camera_info_topic" value="/camera/color/camera_info" />

        <!-- Pass approx_sync parameter for synchronized topics -->

        <arg name="approx_sync" value="true" />

        <!-- Enable RTAB-Map's incremental memory to build a map -->

        <param name="Mem/IncrementalMemory" value="true" /> <!-- Enable map generation -->

        <param name="Rtabmap/Localize" value="false" /> <!-- Disable localization (we're mapping, not localizing) -->

    </include>

    <!-- Launch RViz for visualization -->

    <node name="rviz" pkg="rviz" type="rviz" />

</launch>

Localization Mode:

<?xml version="1.0"?>

<launch>

    <!-- Include the RealSense camera launch file -->

    <include file="$(find realsense2_camera)/launch/rs_camera.launch">

        <!-- Pass necessary arguments if required -->

        <arg name="align_depth" value="true" />

        <arg name="enable_sync" value="true" />

    </include>

    <!-- Include the RTAB-Map launch file for localization mode -->

    <include file="$(find rtabmap_launch)/launch/rtabmap_new.launch">

     <!-- Localization Mode -->

     <arg name="localization"            default="true"/>

        <arg name="rtabmap_args" value="--Grid/NoiseFilteringRadius 0.15 --Grid/NoiseFilteringMinNeighbors 2 --Grid/DepthMax 3" />

        <param  if="$(arg localization)" name="Mem/IncrementalMemory" type="string" value="false"/>

       <param name="Mem/InitWMWithAllNodes" type="string" value="$(arg localization)"/>

        <param name="Mem/IncrementalMemory" value="false" /> <!-- Disable incremental memory for localization -->

        <param name="RGBD/Thread/Enabled" value="true" /> <!-- Enable processing thread -->

        <!-- Pass the camera topics -->

        <arg name="depth_topic" value="/camera/aligned_depth_to_color/image_raw" />

        <arg name="rgb_topic" value="/camera/color/image_raw" />

        <arg name="camera_info_topic" value="/camera/color/camera_info" />

        <!-- Pass approx_sync parameter for synchronized topics -->

        <arg name="approx_sync" value="true" />

        <!-- Prevent resetting the database -->

        <param name="Rtabmap/DatabasePath" value="~/.ros/rtabmap.db" /> <!-- Point to the pre-existing map database -->

        <param name="Rtabmap/SaveData" value="true" /> <!-- Prevent overwriting the map -->

    </include>

    <!-- Run the ArUco pose detection Python script -->

    <node name="run_aruco_pose_detection" pkg="rs_rtab" type="aruco_cube_pose.py" output="screen" />

    <!-- Launch RViz for visualization -->

    <node name="rviz" pkg="rviz" type="rviz" />

</launch>

Make sure you already mapped the environment before running the localization script.

To run these launch files run:
roslaunch mapping.launch

roslaunch localization.launch