It seems like you are trying to get the value of the text field and set it to the lookup field on the CRM form. Well, it is not possible to set the single line of text field's value (i.e. string) to the lookup field in Dynamics 365 CRM.
But assuming you are having a country entity and want to set the lookup of the country based on the value entered in the text field.
So, in that case, you can first retrieve the country record using Xrm.WebApi.retrieveMultipleRecords() method based on the name entered in text field.
You can use this retrieved record id, record name, and entity type to set the lookup field value.
Note: You need to make sure that the value entered in the text field must be present in the country entity records. Else, it will not return any result.
The below code shows how to set the lookup field value using JavaScript in Dynamics 365 CRM:
var setLookupValue = [];
setLookupValue[0] = new Object();
setLookupValue[0].id = recordId;
setLookupValue[0].name = recordName;
setLookupValue[0].entityType = entityLogicalName ;
Xrm.Page.getAttribute("LookupFiels_LogicalName").setValue(setLookupValue );
You can see the following link to know more about how to retrieve records using Xrm.WebApi.retrieveMultipleRecords :
https://docs.microsoft.com/en-us/powerapps/developer/model-driven-apps/clientapi/reference/xrm-webapi/retrievemultiplerecords
Hope this helps.
Thanks!
