Hi Kydyrov,
You can run the following script in ArcGIS Pro:
import arcpy
from arcpy import env
env.workspace = r"C:\temp\python\test.gdb"
fc = "Parks"
for field in arcpy.ListFields(fc):
print("Updating field: {0}".format(field.name))
try:
arcpy.AlterField_management(fc, field.name, "", str(field.aliasName).lower())
except:
print("\tUnable to update {0}".format(field.name))
pass