ArcGIS Pro 2.7 API Reference Guide
FindLayer Method (Map)
Example 

ArcGIS.Desktop.Mapping Namespace > Map Class : FindLayer Method
The URI of the layer. Which is unique identifier for each layer
(optional) When true the search continues in group layers. (default value = true)
Finds a layer using a URI.
Syntax
public Layer FindLayer( 
   string layerURI,
   bool recurive
)
Public Function FindLayer( _
   ByVal layerURI As String, _
   Optional ByVal recurive As Boolean _
) As Layer

Parameters

layerURI
The URI of the layer. Which is unique identifier for each layer
recurive
(optional) When true the search continues in group layers. (default value = true)

Return Value

Example
Find a layer.
//Finds layers by name and returns a read only list of Layers
IReadOnlyList<Layer> layers = aMap.FindLayers("cities", true);

//Finds a layer using a URI.
//The Layer URI you pass in helps you search for a specific layer in a map
var lyrFindLayer = MapView.Active.Map.FindLayer("CIMPATH=map/u_s__states__generalized_.xml");

//This returns a collection of layers of the "name" specified. You can use any Linq expression to query the collection.  
var lyrExists = MapView.Active.Map.GetLayersAsFlattenedList()
                   .OfType<FeatureLayer>().Any(f => f.Name == "U.S. States (Generalized)");
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

Map Class
Map Members