well, you wrote "I cannot add those tags in views." I assumed you were talking about Dynamics 365 standard views and with that is normal to don't be able to "aggregate" related records (as the tags in your situation) inside the main record that is shown.
It's not a visual aspect problem, is how you decide to store the information. Of course creating an entity and add an N:N relationship is from a data aspect (or db normalization if you prefer) the best thing you can do.
Beside how the data is internally stored, you have two problems:
1) how normal users are able to create/update/delete these tags, if you use a N:N relationship you have the standard grids, and if you use a different system you have PCF, is not only an UI/UX problem, is a data entry problem you are facing.
2) how the reporting is done, standard views I already replied above, if you do a report (with the classic report engine or with Power BI) you will have more complexity when you have an additional entity but is doable, different if you have a text field that hold the value (in the format you wish or with a simply transformation you can apply), 99% you use the report to visualize the data (not talking here about inline editing you can achieve with Power BI)
the downside you can face if you store the values in a single field is how you search for records with only a specific value, but lucky for us the advanced find filtering is good enough to solve our problems.
for example you have two records with the following tags
"A", "B", "D"
and
"B", "C", "E"
and you want the records containing "B", because the field is text you can use the Contains clause.
Problem, what if we have values like
Alpha, AlphaChannel, Beta
and when we search for Alpha (Contains) we don't want AlphaChannel to be returned?
that can be solved (not completely but is a start) by storing (note: storing, visualization can be transformed) like
"Alpha", "AlphaChannel", "Beta"
and the filter needs to contains the quotation marks
of course this only if you are aware that this kind of tags can happen in your configuration.
No solution is 100% perfect otherwise everybody would use that.
hope it helps