Space is removing at end of the line
If you really want to have that specific space and line break, you should not rely on enviroment settings, but explicitly specify it:

insert into emp values(1,'&lt;p style="font-weight: bold; margin-top: 10px;"&gt;Mithrivanam, Ameerpet, ' || chr(10) ||
'Hyderabad, Telangana, 500018&lt;/p&gt;');