SELECT * FROM Addresses WHERE  Address_1 not LIKE '%[^a-z,A-Z]%'
SELECT * FROM Addresses WHERE  Address_1 not LIKE '%[^a-zA-Z]%'
SELECT * FROM Addresses WHERE  Address_1  LIKE '%[^a-z,A-Z]%'
SELECT * FROM Addresses WHERE  Address_1  LIKE '%[a-z,A-Z]%'
.................

SELECT Address_1, cast(Address_1 as varchar(100)) COLLATE SQL_Latin1_General_CP1253_CI_AI as convertedAddress FROM Addresses WHERE  Address_ID IN (27,28)

Result:

Address_1	                convertedAddress
1234 boul de la Métropole	1234 boul de la Metropole
5678 rue Bériault	        5678 rue Beriault

SELECT * FROM Addresses WHERE  convert(VARCHAR(1000), Address_1) != cast(Address_1 as nvarchar(1000)) COLLATE SQL_Latin1_General_CP1253_CI_AI

declare @FrenchChars table
(
id int,
FrChr nchar(1)
)
insert into @FrenchChars
select REPLACE(m,';',''),n
from
(
values
('224;','à'),
('194;','Â'),
('226;','â'),
('198;','Æ'),
('230;','æ'),
('199;','Ç'),
('231;','ç'),
('200;','È'),
('232;','è'),
('201;','É'),
('233;','é'),
('202;','Ê'),
('234;','ê'),
('203;','Ë'),
('235;','ë'),
('206;','Î'),
('238;','î'),
('207;','Ï'),
('239;','ï'),
('212;','Ô'),
('244;','ô'),
('140;','Œ'),
('156;','œ'),
('217;','Ù'),
('249;','ù'),
('219;','Û'),
('251;','û'),
('220;','Ü'),
('252;','ü'),
('171;','«'),
('187;','»'),
('128;','€'),
('8355;','?')
)t(m,n)


--select * from @FrenchChars


declare @tbl table

(Address_1	      varchar(1000),
convertedAddress varchar(1000)
)

insert @tbl
values('1234 boul de la Métropole',	'1234 boul de la Metropole'),
('5678 rue Bériault','5678 rue Beriault')


select *
from @tbl t
where exists(select 1
from @FrenchChars 
where t.Address_1 LIKE '%' + FrChr + '%'
)

output
-------------------------------------------
Address_1	                 convertedAddress
1234 boul de la Métropole	1234 boul de la Metropole
5678 rue Bériault	        5678 rue Beriault