How to handle the params for accepts_nested_attributes_for for has_many association containing a lot of fields on both associated table

I have user model which has has_many association with building model. Initially I was creating the user and the building seperately by using user.create and user.buildings.create because there were some field in the table such that if that field is true then only it create the building and in building also there were condition that if a conditional field in building will be true then more field data will be added to the building. Everything was running smooth till a user create a single building. But when a user started to create more building it bursts the code. Below is the code of users_controller

def create
      role = Role.find_by(id: params[:user][:role_id])
      if role.nil?
        render json: { error: 'invalid role' }, status: :unprocessable_entity
      else
        user = User.new(user_params)
        user.role_id = role.id
        ActiveRecord::Base.transaction do
          if user.save
            # If the user is a technician, handle equipment_params
            if role.name.downcase == 'technician'
              equipment_ids = params[:user][:equipment_id]
              handle_technician_params(user, equipment_ids)
            end
            # If the user is a customer, handle customer_params
            if role.name.downcase == 'customer'
              handle_customer_params(user)
            end
            # Generate a new authentication token for the user
            token, refresh_token = generate_tokens(user.id)
            render json: {  message: 'User created successfully', authentication_token: token, user: user, meta: {photos: UserSerializer.new(user) }}, status: :ok
          else
            render json: { errors: user.errors.full_messages }, status: :unprocessable_entity
          end
        end
      end
    end
def handle_customer_params(user)
      if user_params[:is_customer_direct_point_of_contact] == 'true'
        handle_building_params(user)
      else
        handle_service_params(user)
      end
    end

    def handle_building_params(user)
      building_params = params.require(:building).permit(:service_address_line1, :service_address_line2, :service_zip_code, service_images: [])
      building = user.buildings.create(building_params)
    end
    def handle_service_params(user)
      service_params = params.require(:building).permit(:service_address_line1, :service_address_line2, :service_zip_code, :name, :phone_number, :email, :tax_id, service_images: [])
      building = user.buildings.create(service_params)
    end

I tried to change it to use accepts_nested_attributes_for for direct creating the user and building but did'nt understand how to do that. Is there any also other way to do that?